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Vaping and e-cigarettes

Vaping and e-cigarettes
Authors:
Nancy A. Rigotti, MD
Krishna P Reddy, MD
Section Editors:
Mark D Aronson, MD
Umur Hatipoglu, MD, MBA
Deputy Editor:
Sara Swenson, MD
Literature review current through: May 2024.
This topic last updated: Mar 14, 2024.

INTRODUCTION — Electronic cigarettes (e-cigarettes or ECs) are battery-operated devices that heat a liquid usually containing nicotine, producing an aerosol that the user inhales (figure 1) [1]. ECs entered the market in 2003 in China and entered the United States and European markets in 2006 [2]. In many areas, ECs entered the market as consumer products without government regulation. Initially produced by small companies, tobacco companies have bought some of these companies and are developing these products [3]. They are available both online and in traditional retail outlets.

There is uncertainty about the long-term health effects of ECs and whether they will help individual tobacco users to stop smoking [4-7]. There are also public health concerns, including concerns about the effect of ECs on smoking prevalence and their potential use by children as a gateway to nicotine dependence and subsequent combustible tobacco product use [8].

This topic will provide an overview of ECs, including information about devices, use, components, adverse health effects, use in smoking cessation, impact on public health, as well as suggestions for patient counseling. An overview of smoking cessation and pharmacotherapies and behavioral therapies for smoking cessation are discussed in detail in the following topic reviews:

●(See "Overview of smoking cessation management in adults".)

●(See "Pharmacotherapy for smoking cessation in adults".)

●(See "Behavioral approaches to smoking cessation".)

●(See "Prevention of smoking and vaping initiation in children and adolescents", section on 'Vaping nicotine'.)

●(See "Tobacco and nicotine use in pregnancy: Cessation strategies and treatment options".)

●(See "Cigarette and tobacco products in pregnancy: Impact on pregnancy and the neonate".)

ELECTRONIC NICOTINE DELIVERY SYSTEMS

E-cigarette devices — ECs are a type of electronic nicotine delivery system (ENDS) consisting of a cartridge containing a liquid, an atomizer (vaporization chamber with a heating element), and a battery (figure 1) [9].

The user activates the atomizer either by inhaling or by pressing a button, depending on the device characteristics. The atomizer then heats and aerosolizes the liquid in the cartridge, creating an aerosol that emulates but is not tobacco smoke. This process simulates the experience of smoking a conventional cigarette, but no combustion occurs. The term "vaping" is used to distinguish the process from smoking a conventional cigarette. The term "dripping" is used to describe a technique in which a couple of drops of the liquid in the EC cartridge are dripped directly onto the atomizer's heating element to create a cloud of aerosol that can be inhaled [10].

ECs originally were designed to resemble conventional cigarettes, but EC technology is rapidly evolving. Newer versions resemble cigarettes less and feature rechargeable batteries as well as heating elements and refillable cartridges that can deliver higher concentrations of nicotine (figure 2) [1].

●First-generation products – First-generation ECs mimic the shape and size of conventional cigarettes and may be referred to as "cigalikes." They are neither rechargeable nor refillable and are discarded after they stop producing aerosol.

●Second-generation products – Second-generation ECs are larger than conventional cigarettes and are either pen-style (medium size) or tank-style (large size). Both feature rechargeable batteries that may have a switch or electronic circuits that allow users to regulate the frequency and length of puffs or the power delivery to the atomizer. The cartridges in second-generation ECs are refillable and allow the user to adjust the contents of the EC liquid.

●Third-generation products – Third-generation ECs are similar to second-generation devices but allow for more custom modifications [1]. They are known as "personalized vaporizers." There are a range of options for cartridges and atomizers; some devices allow the user to adjust the resistance of the atomizer, which produces higher heating temperatures. Users can also pair different atomizers with high-capacity batteries to increase aerosol production and battery life.

●Fourth-generation products – "Pod-mod devices" are a type of EC that increased in popularity among adolescents in 2018 [11]. These rechargeable devices have replaceable cartridges that contain nicotine and flavorings. A popular brand is JUUL, a device that resembles a USB flash drive. JUUL's small size and discreet appearance make it easy for the device use to go unnoticed in school settings. JUUL devices can deliver higher concentrations of nicotine without throat irritation because they contain nicotine in a form that is less irritating to the throat.

●Newer disposable devices – Similar to first-generation products, these small, often brightly colored devices are non-rechargeable and disposable, and they are available in many flavors (eg, fruit, candy, mint) [12-14]. They are inexpensive and popular among youths due to low cost, flavors, and attractive product design and decoration.

E-cigarette liquid components — Unlike conventional cigarettes, which burn tobacco and generate smoke, ECs have a cartridge containing a liquid (sometimes referred to as "vape juice," "e-juice," or "e-liquid"). The liquid is heated to produce an aerosol the user inhales [1]. Nicotine ECs contain nicotine and other constituents, some with carcinogenic potential [1,15-18]:

●Nicotine – The nicotine content of ECs and liquids varies and usually ranges from none (nicotine free) up to 36 mg/mL, though it can be higher [1,19]. Common nicotine concentrations of EC liquids are 6 mg/mL, 12 mg/mL, 18 mg/mL, or 24 mg/mL. Some EC liquids contain nicotine salts, in which nicotine is combined with an acid [20]. Use of nicotine salts may have a different sensation in a user's throat [20].

●Propylene glycol/glycerol – Propylene glycol or glycerol are humectants that are the main components of most EC liquids; some products may use ethylene glycol [21].

●Flavorings – ECs may have added characterizing flavors. More than 7000 flavors are available, including candy, fruit, soda, and alcohol flavors [22]. Flavorings may increase the attractiveness of ECs to youths, especially those who do not already smoke [23].

Metals such as tin, lead, nickel, chromium, manganese, and arsenic have been found in some EC liquids and aerosol [24,25]. Other compounds detected include tobacco-specific nitrosamines, carbonyl compounds, metals, volatile organic compounds, and phenolic compounds [1,18,26,27]. Vaping devices can be used to aerosolize tetrahydrocannabinol or cannabinoid (CBD) oils.

Heat-not-burn tobacco products — Another type of heating device is used in heat-not-burn (HNB) tobacco products. The device heats tobacco to a much lower temperature than that of a conventional tobacco cigarette. In July 2020, the US Food and Drug Administration (FDA) approved the manufacturer's request to market these devices with the claim that they reduce exposure to tobacco toxins [28]. HNB products are described separately. (See "Patterns of tobacco use", section on 'Heat-not-burn tobacco products'.)

PREVALENCE AND PATTERNS OF USE

Prevalence

●Adults – In 2021, the prevalence of EC use was 4.5 percent among United States adults, according to the National Health Interview Survey (NHIS) [29].

The prevalence of EC use is highest among young adults (ages 18 to 24 years) and declines with increasing age [29]. As an example, in the 2021 Behavioral Risk Factor Surveillance System, a national telephone survey of 414,755 United States adults, the prevalence of current and daily EC use was 6.9 and 3.5 percent, respectively [30]. However, among young adults (ages 18 to 24), 18.6 percent reported current EC use and over 9 percent reported daily use.

The prevalence of EC use in the United States has gradually trended upward over time. As an example, in the NHIS, the prevalence of current EC use among adults increased from 3.7 to 4.5 percent between 2013 and 2021 [29,31-34]. Similarly, in young adults (ages 18 to 24 years), current EC use increased from 7.6 to 11 percent between 2018 and 2021 [29].

●Youth – ECs are the most commonly used tobacco product among youth in the United States (figure 3 and figure 4). The use of ECs and other tobacco products by children and adolescents is discussed separately. (See "Prevention of smoking and vaping initiation in children and adolescents", section on 'Epidemiology'.)

Patterns of use

●Adults – EC use (ever or current use) is more common among younger age groups, males, and non-Hispanic White adults [34-37].

Although most current adult users of ECs have smoked conventional cigarettes, young adults (aged 18 to 24) are much more likely than older adults to report never having used conventional, or combustible, cigarettes [35,37,38]. As an example, in a 2021 survey of 414,755 randomly sampled United States participants, only 20.7 percent of adults who reported currently using ECs had never used combustible cigarettes [30]. In contrast, 53 percent of those aged 21 to 24 years and 72 percent of those aged 18 to 20 years who currently used ECs reported no prior use of combustible cigarettes. Since 2016, young adults with established tobacco use have shifted from predominantly using conventional cigarettes to vaping ECs [14,38-41].

Among those who currently smoked conventional cigarettes, the prevalence of EC use remained stable from 2014 to 2018. However, among adults who previously smoked conventional cigarettes, EC use increased from 4.2 to 5.5 percent from 2017 to 2018 [31]. Similarly, among young adults who previously smoked, current EC use increased from 10.4 to 36.5 percent from 2014 to 2018 [32].

Adults who recently quit smoking are more likely to use ECs regularly than those who formerly smoked [42]. This may be in part because many users of ECs perceive them to be a tool to quit conventional cigarettes or to reduce their risk of tobacco-related disease [37,43,44]. As an example, in a survey of 2501 United States adults who smoked, participants reported a greater interest in using ECs for smoking cessation or reduction than for novelty or to cope with smoking restrictions [45].

EC use is uncommon among older adults who have never smoked cigarettes. As an example, among adults who had never smoked cigarettes, only 6.5 percent had ever used ECs and 1.1 percent currently used them [35]. However, EC use in those who never smoked has increased among young United States adults (from 1.5 percent in 2014 to 4.6 percent in 2018) [32].

●Youth – Compared with adults, adolescents who use ECs are more likely to use flavored products and less likely to vape daily or have regularly smoked conventional cigarettes prior to initiating ECs. Patterns of EC use among children and adolescents are discussed separately. (See "Prevention of smoking and vaping initiation in children and adolescents", section on 'Prevalence and trends'.)

ROLE IN SMOKING CESSATION

Our approach — Although substantial evidence documents the efficacy of ECs for smoking cessation, we do not consider them first-line agents for smoking cessation because of the paucity of evidence regarding their health effects with long-term use (see 'Efficacy' below). We offer ECs as a smoking cessation aide in the following situations:

●Patients who have tried to quit by using standard behavioral therapies and pharmacotherapies and been unsuccessful after one or more quit attempts. (See "Pharmacotherapy for smoking cessation in adults", section on 'Initial therapy selection'.)

●Patients who are not ready to set a quit date should be encouraged to try a "reduce-to-quit" approach with varenicline for six months [46]. For individuals who are not successful with this strategy or not ready to quit entirely, we discuss the option of ECs to reduce their health risks.

When patients decide to use ECs to help them stop smoking, we encourage them to transition completely from conventional to electronic cigarettes. We also encourage them to use ECs as a short-term intervention to reduce cravings and nicotine withdrawal symptoms and establish a durable cigarette abstinence.

After patients have stopped smoking conventional cigarettes entirely and are confident they will not return to smoking them, we encourage them to discontinue using ECs because of uncertainty about their long-term health effects [47].

ECs may appeal to individuals who want to stop smoking because they look and taste more like conventional cigarettes and permit the user to continue the hand-to-mouth ritual of smoking [48]. Users of ECs report reduced conventional cigarette cravings and nicotine withdrawal symptoms [49,50].

However, ECs could potentially deter people from using smoking cessation medications with more robust records of safety and efficacy [51-53]. Moreover, studies suggest that significant proportions of those who start ECs for smoking cessation continue to use them and thereby remain dependent on nicotine [53-56]. Although exposures to toxins from ECs are substantially lower than those from conventional cigarettes, the long-term risks of EC use remain uncertain. (See 'Aerosol (also known as vapor) exposure' below.)

The 2020 guidelines from the American Thoracic Society recommend using proven pharmacotherapy (ie, varenicline) for smoking cessation, rather than ECs [46]. The United States Preventive Services Task Force concluded in 2021 that the evidence was insufficient to determine the benefits and harms of ECs for smoking cessation [46,57].

Efficacy — Data from meta-analyses and randomized trials document the efficacy and short-term safety of ECs for smoking cessation. Their safety with long-term use is less clear [1,7,57-59]. Early trials of ECs used products containing lower nicotine doses, which may limit their generalizability to the higher nicotine dose products that are currently available [60].

●Nicotine versus nonnicotine e-cigarettes – ECs that contain nicotine appear superior to ECs without nicotine, based on data from randomized trials. As an example, in a meta-analysis of six trials with 1613 participants, participants randomized to nicotine-containing ECs were more likely to quit smoking, compared with those randomized to devices without nicotine (quit rate 11 versus 9.6 percent; relative risk increase 1.46; 95% CI 1.09-1.96) [55]. Rates of adverse events were comparable in the two groups.

●Compared with usual care – ECs also are superior to usual care or behavioral counseling interventions [7,58-60]. As an example, in a meta-analysis of nine randomized trials that included 5024 participants, nicotine-containing ECs resulted in higher quit rates than usual care or behavioral support (quit rate 10.3 versus 6.3 percent; relative risk increase 1.88; 95% CI 1.56-2.25) [55]. Rates of adverse events were significantly higher in the groups randomized to ECs (84 versus 66 percent).

●As addition to behavioral counseling – ECs may increase quit rates when added to behavioral interventions. In an open-label trial of 1246 adults who were motivated to stop smoking, the addition of ECs to standard smoking cessation counseling resulted in higher rates of biochemically confirmed continuous abstinence at six months, compared with counseling alone (29 versus 16 percent; relative risk [RR] 1.77; 95% CI 1.43-2.20) [56]. However, self-reported abstinence from all nicotine was higher in the control than in the intervention group (34 versus 20 percent) because many of those assigned to ECs were still using them after 12 months. An earlier study reported similar results [7].

●Compared with varenicline – Limited data suggest that ECs may be noninferior to varenicline for smoking cessation [61,62]. As an example, in an open-label trial of 1068 participants, biochemically validated abstinence rates in the EC group were noninferior to those in the varenicline group at six months (15.7 versus 14.2 percent; odds ratio [OR] 1.92; 95% CI 1.15-3.21) [63]. Of note, 63 percent of those randomized to ECs were still using them at six months. These findings await confirmation in larger randomized trials.

●Compared with nicotine replacement therapy – Data from meta-analyses and randomized trials indicate that ECs are superior to nicotine replacement therapy (NRT) [54,59]. As an example, in a 2024 meta-analysis of seven trials with 2544 participants, quit rates were higher in those randomized to nicotine ECs compared with NRT (17.6 versus 10.2 percent; RR 1.59; 95% CI 1.30-1.93) [55]. In these trials, NRT consisted of the nicotine patch, or individual participants chose their preferred NRT product (eg, patch, gum, lozenge, nasal spray). It is unclear how many participants used combination NRT (nicotine patch plus short-acting nicotine gum or lozenge), which is more efficacious than single-agent NRT (see "Pharmacotherapy for smoking cessation in adults", section on 'Efficacy'). A subsequent, open-label randomized trial of 1068 individuals in China also reported higher abstinence rates at six months with nicotine ECs compared with nicotine gum (15.7 versus 8.8 percent; OR 1.92; 95% CI 1.15-3.21) [63].

Smoking reduction — An individual will gain the most benefit if smoking is stopped entirely. However, ECs might have the potential to reduce harm from tobacco-related diseases by replacing or reducing conventional cigarette use [64-66]. There is little evidence to support this hypothesis, and the degree to which smoking reduction must be achieved is not established.

●Replacing conventional cigarettes – The primary benefit hypothesized is a reduction in the negative health consequences of conventional cigarette use for those who switch completely to ECs. This could decrease conventional smoking rates at the population level and should lead to a reduction in tobacco-attributable morbidity and mortality. Theoretically, the reduction in tobacco-attributed morbidity and mortality could be offset by any long-term adverse effects of ECs. (See 'Adverse health effects' below.)

●Dual use – If ECs lead to dual use (with conventional cigarettes), the individual might still reduce their tobacco-attributable risk of chronic disease if they reduce the number of conventional cigarettes smoked. However, the relationship between the amount of conventional cigarette smoking and disease is not strictly linear for all conditions. For example, small amounts of smoke exposure can still increase risk for coronary artery disease [67]. (See "Cigarette smoking and other possible risk factors for lung cancer", section on 'Smoking reduction' and "Benefits and consequences of smoking cessation", section on 'Questionable utility of smoking reduction'.)

COUNSELING FOR PATIENTS — We discuss the following points with patients:

●Recreational use of ECs should not be initiated; individuals who do not smoke should not start using ECs [68].

●EC products should not be bought "off the street," adulterated, or altered (ie, should not have any substances added to the commercially manufactured product) [69]. E-cigarette or vaping product use-associated lung injury has predominantly been associated with vaping of tetrahydrocannabinol products contaminated by vitamin E acetate rather than commercially purchased nicotine-containing ECs. (See "E-cigarette or vaping product use-associated lung injury (EVALI)".)

For those who smoke conventional cigarettes who are interested in using ECs for smoking cessation, we additionally discuss the following:

●All individuals who express an interest in smoking cessation should receive support for their desire to stop smoking, regardless of the method that they choose. (See "Overview of smoking cessation management in adults".)

●We encourage patients to try "first-line" smoking cessation measures (eg, behavioral support plus pharmacotherapy with varenicline, combination nicotine replacement therapy, cytisine [not available in US], bupropion) rather than ECs because of the lack of evidence regarding the latter's safety with long-term use. Those who previously failed conventional treatments should be assessed for proper medication use and/or consider second-line therapies. Individuals who are unwilling to use these agents for smoking cessation or who have tried them and been unable to quit may consider using ECs to help them stop smoking. (See "Overview of smoking cessation management in adults" and "Pharmacotherapy for smoking cessation in adults".)

●People who choose to use ECs to quit smoking should switch completely rather than using both conventional and electronic cigarettes. A complete switch to using nicotine-containing ECs may be less harmful than continuing to smoke conventional cigarettes, at least in the short term. Those who switch to ECs should eventually plan to quit using them, so long as that does not lead to relapse (ie, smoking conventional cigarettes). Dual use of conventional cigarettes and ECs is not likely to substantially reduce the risk of tobacco-related disease.

EC use should not be permitted in hospitals, health care facilities, or other venues where conventional cigarettes are not allowed. Nicotine replacement products (not ECs) should be used to manage nicotine withdrawal symptoms in hospitalized patients. (See "Pharmacotherapy for smoking cessation in adults", section on 'Nicotine replacement therapy' and "Pharmacotherapy for smoking cessation in adults", section on 'Hospitalized patients'.)

Policy statements from the American Cancer Society, American Heart Association, United States Preventive Services Task Force, and other groups provide guidance on addressing EC use in clinical practice [70-75]. The Centers for Disease Control and Prevention (CDC) also provides guidance to clinicians and the public about ECs [76].

For children, a report by the Surgeon General, "Know the risks, e-cigarettes and young people," includes information sheets that clinicians may use to educate patients and a tip sheet for parents [77]. Information for adolescents and their caregivers about ECs is available from the CDC website, including content about health risks and other frequently asked questions and advice for caregivers on how to keep kids EC free [78]. Additional resources for helping adolescents to quit smoking are discussed separately. (See "Management of smoking and vaping cessation in adolescents", section on 'Self-help programs and educational websites' and "Prevention of smoking and vaping initiation in children and adolescents", section on 'Educational resources'.)

ADVERSE HEALTH EFFECTS — Potential adverse effects of ECs are related to exposure to nicotine as well as to other aerosol components produced by the devices and risks of the actual device.

Nicotine exposure — Nicotine exposure from EC use, as with cigarette smoking, increases heart rate and produces measurable levels of blood cotinine, a nicotine metabolite [49]. (See "Cardiovascular effects of nicotine", section on 'Smoking and cardiovascular risk'.)

The amount of nicotine delivered and the level of nicotine in the blood varies depending on nicotine concentration in the EC liquid, other components in the EC liquid, user experience, puffing intensity, device characteristics, and vaping technique [79]. Experienced EC users tend to take longer puffs and use the device more intensively compared with novice users [80]. As a consequence, they have higher blood nicotine levels that more closely resemble the levels achieved by smoking conventional cigarettes [1,49,50,81,82]. In less-experienced users, however, the nicotine delivered by ECs is consistently lower than nicotine delivered by conventional cigarettes [83,84].

Data on the health consequences of chronic nicotine exposure alone in the absence of cigarette smoking are available from studies of chronic users of nicotine replacement products. These data do not suggest that chronic nicotine exposure increases long-term cardiopulmonary or cancer risk. (See "Cardiovascular effects of nicotine", section on 'Safety of nicotine replacement therapy'.)

Aerosol (also known as vapor) exposure — Commercially manufactured ECs do not expose the user to many of the constituents of cigarette smoke (eg, tars, oxidant gases, and carbon monoxide) that are responsible for many of the tobacco-attributable diseases [51]. However, most manufactured ECs do contain a number of potentially toxic chemical substances [1]. Furthermore, people may refill empty EC cartridges with various substances and carriers that may increase risk of harm when heated for inhalation.

In 2019, the Centers for Disease Control and Prevention reported over two thousand suspected cases of severe lung illnesses (e-cigarette or vaping product use-associated lung injury [EVALI]) linked to the use of EC devices to aerosolize substances for inhalation [69,85-89]. In the majority of cases, tetrahydrocannabinol had been inhaled within three months of symptom onset; many patients had also inhaled nicotine, and some patients had inhaled only nicotine [87]. Refilled EC cartridges obtained via informal or illicit sources and contaminated with vitamin E acetate appear to be most strongly associated with EVALI cases, and vitamin E acetate has been detected in bronchoalveolar lavage fluid samples obtained from affected patients [69,86,90]. EVALI is discussed in greater detail elsewhere. (See "E-cigarette or vaping product use-associated lung injury (EVALI)".)

EC use has also been associated with the development of acute eosinophilic pneumonia. (See "Idiopathic acute eosinophilic pneumonia", section on 'Etiology'.)

Prior to the emergence of EVALI, most experts believed that inhaling EC aerosol was less likely to be harmful (acutely or chronically) than inhaling cigarette smoke [1,2,91]. The consequences of chronic EC aerosol inhalation are largely unknown, and levels of toxic and carcinogenic compounds may vary depending on the EC liquid components and device used [92]. Little is known about the overall safety or the carcinogenic effects of propylene glycol or glycerol when heated and aerosolized. At high temperatures, propylene glycol decomposes and may form propylene oxide, a probable human carcinogen [93]. Glycerol produces the toxin acrolein, though the levels produced are lower than conventional cigarettes [15]. Both propylene glycol and glycerol decompose to form the carcinogens formaldehyde and acetaldehyde, with levels depending on the voltage of the battery used in the EC [92,94].

Other carcinogenic compounds have been found in ECs, but in trace amounts that are much lower than levels found in conventional cigarettes. These include tobacco-specific nitrosamines (TSNAs), carbonyl compounds, metals, volatile organic compounds (VOCs), and phenolic compounds [1,18,26,27]. A small observational study found that users of ECs for at least six months (who did not smoke conventional cigarettes) had substantially lower urinary and salivary concentrations of TSNAs and VOCs than did those who smoked conventional cigarettes [81]. It is not known whether the particles in EC aerosol have any toxicity. (See "Secondhand smoke exposure: Effects in adults" and "Secondhand smoke exposure: Effects in children", section on 'Is exposure to e-cigarette vapor harmful?'.)

The long-term cardiovascular risks of EC use are unknown but are thought to be substantially lower than the risks of smoking [58]. Aerosol constituents that may influence this risk include nicotine, oxidizing chemicals, particulate matter, and acrolein [95]. A small observational study found that EC use for at least one year was associated with factors that have been correlated with increased cardiovascular risk: increased oxidative stress and a shift toward sympathetic predominance in cardiac autonomic balance [96]. By contrast, another small study found that, compared with a sham control or nonnicotine EC, acute exposure to an EC containing nicotine was not associated with increased oxidative stress but was associated with increased cardiac sympathetic nerve activity [97]. A randomized control trial found that those who switched from conventional to e-cigarettes had improvement in endothelial function and vascular stiffness within one month [98].

The use of nicotine containing ECs may cause a mild, short-term increase in blood pressure [1,97], although the long-term effects on blood pressure are unclear. (See "Smoking and hypertension", section on 'E-cigarettes and blood pressure'.)

Although limited evidence on the effects of EC aerosol suggests that changes in airway respiratory function are much smaller than those associated with conventional cigarettes, there may be an association with cough and asthma symptoms, particularly among adolescents [1,6,99]. In one survey of over 45,000 students (mean age 14.6 years) in Hong Kong, EC use was associated with respiratory symptoms (cough or phlegm), regardless of cigarette smoking status [100]. Similarly, in a survey of 11th- and 12th-grade students in California, there was an association between self-reported chronic bronchitic symptoms (chronic cough, phlegm, or bronchitis within the past year) and current or past EC use that remained after adjustment for cigarette smoking or secondhand smoke exposure; the risk increased with frequency of current EC use [101]. Among adults, there is some evidence of an association between EC use and respiratory symptoms, although the risk appears to be lower than that with cigarette smoking [102,103].

The effect of inhaling flavorings on respiratory function is also uncertain [104]. Some studies have found a link between cytotoxicity and certain flavorings used in EC liquids, especially sweet and cinnamon flavors [105-109]. Specifically, diacetyl, a chemical associated with respiratory diseases, has been found in sweet-flavored ECs [110]. Cherry-flavored ECs have been found to contain benzaldehyde, a compound that has been associated with respiratory irritation [111].

No observational data examining the long-term risk of cancer from ECs exist; however, the risk of cancer is likely to be much lower in adults who use ECs than in those who smoke conventional cigarettes [1,58,112].

Risks of devices — EC devices have been reported to cause burns, explosive injuries, and chemical injuries [58,113-116].

Several reviews have identified emergency department visits for burns from electronic nicotine delivery systems (ENDS) due to device malfunction either while stored (eg, in a pocket) or during use, resulting in burns to the thigh, groin, face, and/or hand [116,117].

In addition, exposure to EC liquid via oral or parenteral ingestion, or through skin contact, can also cause harm, particularly to young children. Such exposure may commonly cause nausea, vomiting, lethargy, and tachycardia and may even result in seizures, anoxic brain injury, lactic acidosis, and death. (See "Nicotine poisoning (e-cigarettes, tobacco products, plants, and pesticides)".)

CONCERNS RELATED TO YOUTH AND NONSMOKERS — For adolescents and others who are not established cigarette smokers, the primary focus is on the potential risks of EC use [118]. Non-smokers are not using ECs to help them stop using conventional cigarettes, so there is no mitigating harm-reduction. Concerns about the risks of ECs are accentuated by the rapidly increasing prevalence of EC use among youth in the United States (figure 3 and figure 4), with many adolescents reporting very frequent use, including during the school day. (See 'Prevalence' above.)

Specific concerns about EC use by youth include:

●Nicotine dependence – Use of ECs raises the risk of establishing nicotine dependence in novice users, which could ultimately lead to combustible tobacco use. This potential gateway effect is suggested by observations that EC use often precedes conventional cigarette use [119-124]. As examples:

•A systematic review and meta-analysis of longitudinal studies among 17,389 adolescents and young adults aged 14 to 30 years showed that, compared with EC never users, ever users had a higher probability of initiating cigarette smoking (31 versus 8 percent, pooled adjusted odds ratio [OR] 3.50 [95% CI, 2.38-5.16]) [122,125].

•In a prospective study of ninth-grade students, an association was seen between use of ECs and other forms of tobacco and use of conventional cigarettes. After adjusting for other risk factors for smoking, baseline EC use was associated with a greater likelihood of using any combustible tobacco product (OR 2.7, 95% CI 2.0-3.7), including conventional cigarettes (OR 2.7, 95% CI 1.7-4.0), cigars (OR 4.9, 95% CI 3.4-7.0), and hookahs (OR 3.3, 95% CI 2.3-4.6) [119].

Some of these findings may be related to the association between the predisposition of an adolescent or young adult to smoke conventional cigarettes and their predisposition to smoke ECs. However, analysis of psychosocial risk factors suggests that many youth who use ECs are unlikely to have initiated tobacco smoking with cigarettes [126].

●Adverse effects – EC use raises the risk of adverse effects (eg, respiratory symptoms), some of which have been reported particularly among youth [100,101,127]. (See 'Aerosol (also known as vapor) exposure' above and "E-cigarette or vaping product use-associated lung injury (EVALI)".)

In addition, one internet survey of adolescents and young adults found that dual use of cigarettes and ECs may be associated with an increased risk of self-reported infection with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the agent that causes COVID-19 [128].

●Normalizing smoking behavior – EC use may normalize smoking behavior, which might contribute to conventional cigarette use. (See 'Renormalization of smoking behavior' below.)

●The long-term effects of nicotine exposure through EC use only, including the effects of EC use during pregnancy, are not known. (See "Cigarette and tobacco products in pregnancy: Impact on pregnancy and the neonate".)

Given the concerns that EC use may be a gateway to nicotine dependence among adolescents, many public health authorities have recommended restricting EC marketing and advertising to youth and banning flavorings, similar to strategies used to reduce tobacco use by youth [77,129-131]. (See 'Regulatory status' below and "Prevention of smoking and vaping initiation in children and adolescents", section on 'Advertising and media influence'.)

There is ample evidence that ECs have been marketed using many of the strategies previously used by tobacco companies to market conventional cigarettes to youth [132]. For example, ECs have been commonly marketed with flavorings, which appeal to youths and are banned in conventional cigarettes for this reason [22,133]. Exposure to EC marketing has been associated with EC use among youth and young adults [134,135].

These issues are discussed in more detail separately. (See "Prevention of smoking and vaping initiation in children and adolescents", section on 'Vaping nicotine'.)

PUBLIC HEALTH CONCERNS — In 2019, cases of e-cigarette or vaping product use-associated lung injury were reported. After epidemiologic investigation, evidence linked these cases primarily to vaping tetrahydrocannabinol products that had been contaminated with vitamin E acetate rather than to the use of commercially sold nicotine-containing ECs. (See "E-cigarette or vaping product use-associated lung injury (EVALI)".)

Other potential impacts of ECs on public health include concerns include ECs' appeal to youth, their potential to reverse gains in social norms about the acceptability of cigarette smoking ("renormalization"), and the risk of dependence [1,136]. However, dependence appears to be lower than for conventional tobacco cigarettes [1].

In addition, there have been increasing reports of poisoning in children related to ECs and concerns about the possible effects of secondhand exposure to the aerosol. A US Surgeon General's report about the risks of ECs to youth highlights the importance of preventing the initiation of nicotine use by adolescents [77].

Renormalization of smoking behavior — If ECs are allowed where cigarette smoking is not, they could reverse the "de-normalization" of smoking behavior brought about by the spread of smoke-free laws [2,137]. These laws are credited with contributing to reducing smoking prevalence in the United States. Tobacco smoking could be "renormalized" and the public health gains rolled back [138]. In theory, this might discourage the frequency and success of quit attempts, encourage relapse among those who previously smoked, and increase tobacco use initiation rates among youth and young adults. At present, there is no evidence of smoking renormalization.

Nicotine poisoning — EC fluid contains highly concentrated liquid nicotine. Exploratory ingestions in young children and intentional ingestions in adolescents and adults have been associated with life-threatening toxicity and death. The clinical manifestations and initial management of nicotine poisoning are provided in a rapid overview (table 1) and discussed in detail separately. (See "Nicotine poisoning (e-cigarettes, tobacco products, plants, and pesticides)".)

Secondhand aerosol exposure — There are concerns about the potential health consequences of secondhand exposure to EC aerosol due to increases in environmental concentrations of nicotine and particulate matter [1]. However, passive exposure to EC aerosol is expected to be less toxic to bystanders than conventional cigarette smoke [1,139,140]. Aerosol released from ECs will depend on user technique, temperature, EC device, and other factors [141].

There is limited evidence on the health effects of passive EC aerosol exposure. Passive exposure to aerosol produces small increases in serum cotinine, comparable with that from passive exposure to cigarette smoke [142]. (See 'Aerosol (also known as vapor) exposure' above.)

REGULATORY STATUS — Regulation of ECs varies by country and is continually evolving. Multiple organizations have recommended more government regulation [70,71,129,130,143,144]. They have called for regulation that would treat ECs like conventional cigarettes, banning their use where conventional cigarettes are banned and subjecting ECs' content, sales, and marketing to regulatory constraints similar to those that apply to conventional cigarettes. Some have suggested that taxation for ECs should be lower than for conventional cigarettes to encourage adults who smoke conventional cigarettes to switch to ECs for harm reduction [145].

Worldwide — The World Health Organization (WHO) report on ECs suggested that regulations were needed to stop promotion of ECs to nonsmokers and young people, minimize potential health risks to users and nonusers, stop unproven health claims about ECs, and protect existing tobacco control efforts [143]. While the WHO acknowledged that additional research on ECs was needed, it also emphasized the need to restrict EC advertising and indoor use. Some groups have disagreed with the WHO report, suggesting that the risks of ECs were overstated [146,147].

United Kingdom — In the United Kingdom, the Royal College of Physicians Tobacco Advisory Group recommended a balanced regulatory approach that ensures product safety while enabling and encouraging those who smoke to use ECs instead of tobacco to reduce harm to health [148]. The report suggests that while ECs are not harmless, they are likely less harmful than conventional cigarettes [149].

United States — The US Food and Drug Administration (FDA) does not regulate ECs as medical products through the Center for Drug Evaluation and Policy (CDER), which regulates nicotine replacement products such as nicotine patches. EC manufacturers could apply to CDER for approval to market the devices as smoking cessation aids, but no manufacturer has yet done so.

Instead, the FDA regulates ECs through its Center for Tobacco Products (CTP). Initially, the 2009 Family Smoking Prevention and Tobacco Control Act granted the CTP the authority to regulate cigarettes and smokeless tobacco but not other tobacco products, including cigars and ECs [150]. In 2016, the regulation was amended to include any product "made or derived from tobacco that is intended for human consumption," including ECs that contain nicotine but not ECs that are nicotine free [151].

FDA regulations require that EC manufacturers demonstrate that their products meet the FDA standard of providing a net public health benefit or face the possibility of being removed from the market [152]. The FDA voluntarily delayed enforcement of this standard while it developed a process for conducting these evaluations. It required manufacturers to submit an application for approval of EC products by September, 2020 [152]. In September 2021, the FDA announced that it had acted on over 90 percent of applications, issuing denials to over 900,000 flavored products due to health concerns related to their popularity among youth [153]. Subsequently, in October 2021, the FDA for the first time authorized the marketing of some electronic nicotine delivery system (ENDS) products, while noting that this ruling "does not mean these products are safe or 'FDA approved'" [154].

The FDA also requires manufacturers, and in many cases retailers ("vape shops") where EC devices are modified and sold, to disclose the ingredients in their products and demonstrate that they are safe [155,156].

The FDA prohibits the sale of tobacco and EC products to those aged <21 years, sales in vending machines (except in adult-only venues), and distribution of free samples [157]. In addition, there are federal regulations to minimize the risk of exposure of youth to ECs, including prohibition of sales of flavored liquids (other than menthol or tobacco) in devices that use pre-filled cartridges [158,159]. Flavored EC liquids, however, are available for sale in vape shops for use in devices that have refillable tanks. In addition, this ban did not apply to flavored disposable ECs, which have become increasingly popular among youth. Among high school EC users, for example, the percentage who reported using disposable ECs increased from 2.4 percent in 2019 to 26.5 percent in 2020 [14]. The FDA has attempted to remove these flavored disposable ECs from the market but, despite this effort, many remain on the market [160,161].

A number of states and many municipalities have banned the use of ECs in areas where cigarette smoking is also completely banned (with limited exceptions in a few states), and additional states and municipalities have banned EC use in other venues [162]. EC use is also banned on airplanes [163].

Other countries — ECs have been banned in some countries [51]. In Europe, the European Parliament approved a directive that regulates nicotine-containing ECs with concentrations up to 20 mg/mL as tobacco products [164]. ECs with higher nicotine concentrations are regulated as medical devices. The directive includes regulation for the maximum amount of nicotine in EC liquids and requires child tamper-proof packaging.

SOCIETY GUIDELINE LINKS — Links to society and government-sponsored guidelines from selected countries and regions around the world are provided separately. (See "Society guideline links: Smoking cessation, e-cigarettes, and tobacco control".)

INFORMATION FOR PATIENTS — UpToDate offers two types of patient education materials, "The Basics" and "Beyond the Basics." The Basics patient education pieces are written in plain language, at the 5th to 6th grade reading level, and they answer the four or five key questions a patient might have about a given condition. These articles are best for patients who want a general overview and who prefer short, easy-to-read materials. Beyond the Basics patient education pieces are longer, more sophisticated, and more detailed. These articles are written at the 10th to 12th grade reading level and are best for patients who want in-depth information and are comfortable with some medical jargon.

Here are the patient education articles that are relevant to this topic. We encourage you to print or e-mail these topics to your patients. (You can also locate patient education articles on a variety of subjects by searching on "patient info" and the keyword(s) of interest.)

●Basics topics (see "Patient education: Vaping (The Basics)")

SUMMARY AND RECOMMENDATIONS

●E-cigarette devices and liquids – Electronic cigarettes (e-cigarettes or ECs) are electronic devices that usually deliver nicotine; they consist of a cartridge containing a liquid, an atomizer (vaporization chamber with a heating element), and a battery. The user activates the atomizer, which heats the liquid and produces an aerosol (sometimes referred to as a vapor) to inhale (figure 1 and figure 2). Across all brands, the main components in nicotine EC liquids are nicotine, propylene glycol or glycerol, and flavorings. A variety of other compounds have also been identified. (See 'Electronic nicotine delivery systems' above.)

●Prevalence and patterns of use – The use of ECs by adults has increased over the past decade. Although most older adults (aged 25 and older) who use ECs also currently smoke conventional cigarettes, young adults (aged 18 to 24) are much more likely to report never having used conventional cigarettes. Many EC users perceive them to be a tool to quit or reduce their smoking. (See 'Prevalence and patterns of use' above.)

●Role of e-cigarettes in smoking cessation – We encourage adults who smoke to use established pharmacotherapies such as varenicline, bupropion, and nicotine replacement therapies rather than ECs. ECs are reasonable alternatives for adults who have been unable to quit with standard pharmacotherapies and are willing to transition from conventional to electronic cigarettes. Although increasing evidence documents the efficacy of ECs for smoking cessation, their long-term risks remain uncertain. (See 'Role in smoking cessation' above and 'Counseling for patients' above.)

●Patient counseling – Recreational use of ECs should not be initiated. EC products should not be bought "off the street," adulterated, or altered. (See 'Counseling for patients' above.)

●Adverse health effects – Potential adverse effects of ECs are related to exposure to nicotine as well as to other aerosol components produced by the devices and risks of the actual device. No observational data examining the long-term risk of cancer from ECs exist; however, the risk is likely to be much lower in adults who use ECs than in those who smoke conventional cigarettes. (See 'Adverse health effects' above.)

E-cigarette or vaping produce use-associated lung injury has been linked to the use of aerosolized substances in EC devices, such as contamination with vitamin E acetate. (See 'Aerosol (also known as vapor) exposure' above and "E-cigarette or vaping product use-associated lung injury (EVALI)".)

●Public health concerns – Public health concerns regarding ECs include the potential to increase youth initiation of tobacco products (figure 3 and figure 4), renormalize tobacco use in places where cigarette smoking is not acceptable, and lead to nicotine dependence. Accidental nicotine poisoning in children has been reported. The health effects of secondhand aerosol exposure are unknown. (See 'Concerns related to youth and nonsmokers' above and 'Public health concerns' above.)

ACKNOWLEDGMENTS — The UpToDate editorial staff acknowledges Stephen Rennard, MD, and Sara Kalkhoran, MD, MAS, who contributed to an earlier version of this topic review.

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  106. Behar RZ, Davis B, Wang Y, et al. Identification of toxicants in cinnamon-flavored electronic cigarette refill fluids. Toxicol In Vitro 2014; 28:198.
  107. Hua M, Omaiye EE, Luo W, et al. Identification of Cytotoxic Flavor Chemicals in Top-Selling Electronic Cigarette Refill Fluids. Sci Rep 2019; 9:2782.
  108. Farsalinos KE, Romagna G, Allifranchini E, et al. Comparison of the cytotoxic potential of cigarette smoke and electronic cigarette vapour extract on cultured myocardial cells. Int J Environ Res Public Health 2013; 10:5146.
  109. Bahl V, Lin S, Xu N, et al. Comparison of electronic cigarette refill fluid cytotoxicity using embryonic and adult models. Reprod Toxicol 2012; 34:529.
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  111. Kosmider L, Sobczak A, Prokopowicz A, et al. Cherry-flavoured electronic cigarettes expose users to the inhalation irritant, benzaldehyde. Thorax 2016; 71:376.
  112. Rigotti NA. Balancing the Benefits and Harms of E-Cigarettes: A National Academies of Science, Engineering, and Medicine Report. Ann Intern Med 2018; 168:666.
  113. Meernik C, Williams FN, Cairns BA, et al. Burns from e-cigarettes and other electronic nicotine delivery systems. BMJ 2016; 354:i5024.
  114. Brownson EG, Thompson CM, Goldsberry S, et al. Explosion Injuries from E-Cigarettes. N Engl J Med 2016; 375:1400.
  115. Simpson LJ, Lye G. Burns injuries from e-cigarettes kept in pockets. BMJ 2019; 364:l554.
  116. Rossheim ME, McDonald KK, Soule EK, et al. Electronic cigarette explosion/burn and poisoning related emergency department visits, 2018-2019. Am J Emerg Med 2020; 38:2637.
  117. Toy J, Dong F, Lee C, et al. Alarming increase in electronic nicotine delivery systems-related burn injuries: A serious unregulated public health issue. Am J Emerg Med 2017; 35:1781.
  118. Lang AE, Kathuria H, Braillon A, et al. England Is Handing out E-Cigarettes: Is the "Swap to Stop" Tobacco Control Scheme Harm Reduction or Harm Production? Am J Respir Crit Care Med 2023; 208:1024.
  119. Leventhal AM, Strong DR, Kirkpatrick MG, et al. Association of Electronic Cigarette Use With Initiation of Combustible Tobacco Product Smoking in Early Adolescence. JAMA 2015; 314:700.
  120. Primack BA, Soneji S, Stoolmiller M, et al. Progression to Traditional Cigarette Smoking After Electronic Cigarette Use Among US Adolescents and Young Adults. JAMA Pediatr 2015; 169:1018.
  121. Barrington-Trimis JL, Urman R, Berhane K, et al. E-Cigarettes and Future Cigarette Use. Pediatrics 2016; 138.
  122. Soneji S, Barrington-Trimis JL, Wills TA, et al. Association Between Initial Use of e-Cigarettes and Subsequent Cigarette Smoking Among Adolescents and Young Adults: A Systematic Review and Meta-analysis. JAMA Pediatr 2017; 171:788.
  123. Hines JZ, Fiala SC, Hedberg K. Electronic Cigarettes as an Introductory Tobacco Product Among Eighth and 11th Grade Tobacco Users - Oregon, 2015. MMWR Morb Mortal Wkly Rep 2017; 66:604.
  124. Chan GCK, Stjepanović D, Lim C, et al. Gateway or common liability? A systematic review and meta-analysis of studies of adolescent e-cigarette use and future smoking initiation. Addiction 2021; 116:743.
  125. Soneji S. Errors in Data Input in Meta-analysis on Association Between Initial Use of e-Cigarettes and Subsequent Cigarette Smoking Among Adolescents and Young Adults. JAMA Pediatr 2018; 172:92.
  126. Dutra LM, Glantz SA. E-cigarettes and National Adolescent Cigarette Use: 2004-2014. Pediatrics 2017; 139.
  127. Vardavas CI, Anagnostopoulos N, Kougias M, et al. Short-term pulmonary effects of using an electronic cigarette: impact on respiratory flow resistance, impedance, and exhaled nitric oxide. Chest 2012; 141:1400.
  128. Gaiha SM, Cheng J, Halpern-Felsher B. Association Between Youth Smoking, Electronic Cigarette Use, and COVID-19. J Adolesc Health 2020; 67:519.
  129. Walley SC, Jenssen BP, Section on Tobacco Control. Electronic Nicotine Delivery Systems. Pediatrics 2015; 136:1018.
  130. Farber HJ, Nelson KE, Groner JA, et al. Public Policy to Protect Children From Tobacco, Nicotine, and Tobacco Smoke. Pediatrics 2015; 136:998.
  131. Winickoff JP, Winickoff SE. Potential Solutions to Electronic Cigarette Use Among Adolescents. Pediatrics 2016; 138.
  132. Grana RA, Ling PM. "Smoking revolution": a content analysis of electronic cigarette retail websites. Am J Prev Med 2014; 46:395.
  133. Choi K, Forster JL. Beliefs and experimentation with electronic cigarettes: a prospective analysis among young adults. Am J Prev Med 2014; 46:175.
  134. Chen-Sankey JC, Unger JB, Bansal-Travers M, et al. E-cigarette Marketing Exposure and Subsequent Experimentation Among Youth and Young Adults. Pediatrics 2019; 144.
  135. Mantey DS, Cooper MR, Clendennen SL, et al. E-Cigarette Marketing Exposure Is Associated With E-Cigarette Use Among US Youth. J Adolesc Health 2016; 58:686.
  136. Gostin LO, Glasner AY. E-cigarettes, vaping, and youth. JAMA 2014; 312:595.
  137. Glynn TJ. E-cigarettes and the future of tobacco control. CA Cancer J Clin 2014; 64:164.
  138. Fairchild AL, Bayer R, Colgrove J. The renormalization of smoking? E-cigarettes and the tobacco "endgame". N Engl J Med 2014; 370:293.
  139. Pellegrino RM, Tinghino B, Mangiaracina G, et al. Electronic cigarettes: an evaluation of exposure to chemicals and fine particulate matter (PM). Ann Ig 2012; 24:279.
  140. Burstyn I. Peering through the mist: systematic review of what the chemistry of contaminants in electronic cigarettes tells us about health risks. BMC Public Health 2014; 14:18.
  141. Schripp T, Markewitz D, Uhde E, Salthammer T. Does e-cigarette consumption cause passive vaping? Indoor Air 2013; 23:25.
  142. Farsalinos KE, Tsiapras D, Kyrzopoulos S, et al. Acute effects of using an electronic nicotine-delivery device (electronic cigarette) on myocardial function: comparison with the effects of regular cigarettes. BMC Cardiovasc Disord 2014; 14:78.
  143. WHO Framework Convention on Tobacco Control. Electronic nicotine delivery systems: Report by WHO. July 2014. Available at: http://apps.who.int/gb/fctc/PDF/cop6/FCTC_COP6_10-en.pdf?ua=1 (Accessed on April 22, 2022).
  144. Crowley RA, Health Public Policy Committee of the American College of Physicians. Electronic nicotine delivery systems: executive summary of a policy position paper from the American College of Physicians. Ann Intern Med 2015; 162:583.
  145. Chaloupka FJ, Sweanor D, Warner KE. Differential Taxes for Differential Risks--Toward Reduced Harm from Nicotine-Yielding Products. N Engl J Med 2015; 373:594.
  146. Ashton JR. Regulation of electronic cigarettes. BMJ 2014; 349:g5484.
  147. Hawkes N. WHO review exaggerated dangers of e-cigarettes, say specialists. BMJ 2014; 349:g5501.
  148. Royal College of Physicians. Nicotine without smoke: Tobacco harm reduction. Available at: https://www.rcplondon.ac.uk/projects/outputs/nicotine-without-smoke-tobacco-harm-reduction-0 (Accessed on June 01, 2016).
  149. Britton J, Arnott D, McNeill A, et al. Nicotine without smoke-putting electronic cigarettes in context. BMJ 2016; 353:i1745.
  150. Public Law 111-31 - June 22, 2009. Family smoking prevention and tobacco control and federal retirement reform. 111th Congress, June 2009. Available at: www.gpo.gov/fdsys/pkg/PLAW-111publ31/pdf/PLAW-111publ31.pdf (Accessed on December 03, 2014).
  151. Federal Register. Deeming tobacco products to be subject to the Federal Food, Drug, and Cosmetic Act, as amended by the Family Smoking Prevention and Tobacco Control Act; restrictions on the sale and distribution of tobacco products and required warning statements for tobacco products. Available at: https://www.federalregister.gov/articles/2016/05/10/2016-10685/deeming-tobacco-products-to-be-subject-to-the-federal-food-drug-and-cosmetic-act-as-amended-by-the (Accessed on May 09, 2016).
  152. US Food and Drug Administration. FDA denies marketing applications for about 55,00 flavored e-cigarette products for failing to provide evidence they appropriately protect public health. Available at: https://www.fda.gov/news-events/press-announcements/fda-denies-marketing-applications-about-55000-flavored-e-cigarette-products-failing-provide-evidence (Accessed on August 27, 2021).
  153. US Food and Drug Administration. FDA makes significant progress in science-based public health application review, taking action on over 90% of more than 6.5 million 'deemed' new tobacco products submitted. September 2021. Available at: https://www.fda.gov/news-events/press-announcements/fda-makes-significant-progress-science-based-public-health-application-review-taking-action-over-90 (Accessed on September 24, 2021).
  154. US Food and Drug Administration. FDA permits marketing of e-cigarette products, marking first authorization of its kind by the agency. October 2021. Available at: https://www.fda.gov/news-events/press-announcements/fda-permits-marketing-e-cigarette-products-marking-first-authorization-its-kind-agency (Accessed on October 19, 2021).
  155. US Food and Drug Administration. Vaporizers, e-cigarettes, and other electronic nicotine delivery systems (ENDS). Available at: https://www.fda.gov/tobacco-products/products-ingredients-components/vaporizers-e-cigarettes-and-other-electronic-nicotine-delivery-systems-ends (Accessed on January 07, 2020).
  156. US Food and Drug Administration. Interpretation of and compliance policy for certain label requirement: Applicability of certain federal Food, Drug, and Cosmetic Act requirements to vape shops. March 2019. Available at: https://www.fda.gov/regulatory-information/search-fda-guidance-documents/interpretation-and-compliance-policy-certain-label-requirement-applicability-certain-federal-food (Accessed on January 07, 2020).
  157. US Food and Drug Administration. Rules for sales of e-cigarettes, e-liquids, and other electronic nicotine delivery systems (ENDS). Available at: https://www.fda.gov/tobacco-products/retail-sales-tobacco-products/selling-tobacco-products-retail-stores#ecig (Accessed on January 07, 2020).
  158. FDA finalizes enforcement policy on unauthorized flavored cartridge-based e-cigarettes that appeal to children, including fruit and mint. US Food and Drug Administration, January 2020. https://www.fda.gov/news-events/press-announcements/fda-finalizes-enforcement-policy-unauthorized-flavored-cartridge-based-e-cigarettes-appeal-children (Accessed on January 07, 2020).
  159. US Food and Drug Administration. FDA warns manufacturers and retailers to remove certain e-cigarette products targeted to youth from the market. April 2020. Available at: https://www.fda.gov/news-events/press-announcements/fda-warns-manufacturers-and-retailers-remove-certain-e-cigarette-products-targeted-youth-market (Accessed on April 27, 2020).
  160. US Food and Drug Administration. FDA notifies companies, including Puff Bar, to remove flavored disposable e-cigarettes and youth-appealing e-liquids from market for not having required authorization. 2020. Available at: https://www.fda.gov/news-events/press-announcements/fda-notifies-companies-including-puff-bar-remove-flavored-disposable-e-cigarettes-and-youth (Accessed on March 04, 2021).
  161. Maloney J. Puff Bar defies FDA crackdown on fruity e-cigarettes by ditching the tobacco. Wall Street Journal 2021. Available at: https://www.wsj.com/articles/puff-bar-defies-fda-crackdown-on-fruity-e-cigarettes-by-ditching-the-tobacco-11614681003 (Accessed on March 04, 2021).
  162. American Nonsmokers' Rights Foundation. States and municipalities with laws regulating use of electronic cigarettes. Available at: https://no-smoke.org/wp-content/uploads/pdf/ecigslaws.pdf (Accessed on September 14, 2018).
  163. US Department of Transportation. DOT issues new flight safety rule for e-cigarettes. October 2015. Available at: https://www.transportation.gov/briefing-room/dot-issues-new-flight-safety-rule-e-cigarettes (Accessed on May 20, 2016).
  164. European Commission. Revision of the Tobacco Products Directive. Available at: https://ec.europa.eu/health/tobacco/product-regulation/implementing-tobacco-products-directive-directive-201440eu/revision-tobacco-products-directive_en (Accessed on December 08, 2014).
Topic 98400 Version 84.0

References

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6 : What are the respiratory effects of e-cigarettes?

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8 : Regulating Vaping - Policies, Possibilities, and Perils.

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10 : E-Cigarettes and "Dripping" Among High-School Youth.

11 : Adolescents' Use of "Pod Mod" E-Cigarettes - Urgent Concerns.

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13 : E-cigarette Unit Sales, by Product and Flavor Type - United States, 2014-2020.

14 : E-cigarette Use Among Middle and High School Students - United States, 2020.

15 : Levels of selected carcinogens and toxicants in vapour from electronic cigarettes.

16 : Metal and silicate particles including nanoparticles are present in electronic cigarette cartomizer fluid and aerosol.

17 : Determination of tobacco-specific nitrosamines in replacement liquids of electronic cigarettes by liquid chromatography-tandem mass spectrometry.

18 : Electronic nicotine delivery system design and aerosol toxicants: A systematic review.

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20 : Characterization of Nicotine Salts in 23 Electronic Cigarette Refill Liquids.

21 : Chemical hazards present in liquids and vapors of electronic cigarettes.

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23 : Four hundred and sixty brands of e-cigarettes and counting: implications for product regulation.

24 : Metal Concentrations in e-Cigarette Liquid and Aerosol Samples: The Contribution of Metallic Coils.

25 : Metal/Metalloid Levels in Electronic Cigarette Liquids, Aerosols, and Human Biosamples: A Systematic Review.

26 : Analysis of electronic cigarette cartridges, refill solutions, and smoke for nicotine and nicotine related impurities.

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34 : Tobacco Product Use Among Adults - United States, 2020.

35 : Tobacco Product Use Among Adults - United States, 2020.

36 : Tobacco Product Use Among Middle and High School Students - United States, 2011-2017.

37 : Demographic Characteristics, Cigarette Smoking, and e-Cigarette Use Among US Adults.

38 : Shift From Smoking Cigarettes to Vaping Nicotine in Young Adults.

39 : e-Cigarette Use Among Youth in the United States, 2019.

40 : Prevalence and Distribution of E-Cigarette Use Among U.S. Adults: Behavioral Risk Factor Surveillance System, 2016.

41 : Electronic cigarette use among US adults in the Population Assessment of Tobacco and Health (PATH) Study, 2013-2014.

42 : Patterns of Electronic Cigarette Use Among Adults in the United States.

43 : Patterns of and reasons for electronic cigarette use in primary care patients.

44 : Reasons for current E-cigarette use among U.S. adults.

45 : Cigarette users' interest in using or switching to electronic nicotine delivery systems for smokeless tobacco for harm reduction, cessation, or novelty: a cross-sectional survey of US adults.

46 : Initiating Pharmacologic Treatment in Tobacco-Dependent Adults. An Official American Thoracic Society Clinical Practice Guideline.

47 : E-Cigarettes as a Smoking Cessation Aid - Toward Common Ground and a Rational Approach.

48 : E-cigarette versus nicotine inhaler: comparing the perceptions and experiences of inhaled nicotine devices.

49 : Electronic cigarettes: effective nicotine delivery after acute administration.

50 : Acute electronic cigarette use: nicotine delivery and subjective effects in regular users.

51 : E-cigarettes: a scientific review.

52 : Electronic Cigarettes for Smoking Cessation - Have We Reached a Tipping Point?

53 : Electronic Cigarettes for Smoking Cessation-A Clinician's Dilemma.

54 : A Randomized Trial of E-Cigarettes versus Nicotine-Replacement Therapy.

55 : Electronic cigarettes for smoking cessation.

56 : Electronic Nicotine-Delivery Systems for Smoking Cessation.

57 : Interventions for Tobacco Smoking Cessation in Adults, Including Pregnant Persons: US Preventive Services Task Force Recommendation Statement.

58 : Interventions for Tobacco Smoking Cessation in Adults, Including Pregnant Persons: US Preventive Services Task Force Recommendation Statement.

59 : Electronic cigarettes for smoking cessation.

60 : Randomized Trials of e-Cigarettes for Smoking Cessation.

61 : Pharmacological and electronic cigarette interventions for smoking cessation in adults: component network meta-analyses.

62 : Smoking cessation medicines and e-cigarettes: a systematic review, network meta-analysis and cost-effectiveness analysis.

63 : Efficacy of Electronic Cigarettes vs Varenicline and Nicotine Chewing Gum as an Aid to Stop Smoking: A Randomized Clinical Trial.

64 : E-cigarettes--aid to smoking cessation or smokescreen?

65 : Electronic Cigarettes: Perhaps the Devil Unknown Is Better Than the Devil Known.

66 : Effect of an electronic nicotine delivery system with 0, 8, or 36 mg/mL liquid nicotine versus a cigarette substitute on tobacco-related toxicant exposure: a four-arm, parallel-group, randomised, controlled trial.

67 : Effect of an electronic nicotine delivery system with 0, 8, or 36 mg/mL liquid nicotine versus a cigarette substitute on tobacco-related toxicant exposure: a four-arm, parallel-group, randomised, controlled trial.

68 : Effect of an electronic nicotine delivery system with 0, 8, or 36 mg/mL liquid nicotine versus a cigarette substitute on tobacco-related toxicant exposure: a four-arm, parallel-group, randomised, controlled trial.

69 : Effect of an electronic nicotine delivery system with 0, 8, or 36 mg/mL liquid nicotine versus a cigarette substitute on tobacco-related toxicant exposure: a four-arm, parallel-group, randomised, controlled trial.

70 : Electronic cigarettes. A position statement of the forum of international respiratory societies.

71 : Electronic nicotine delivery systems: a policy statement from the American Association for Cancer Research and the American Society of Clinical Oncology.

72 : Electronic nicotine delivery systems: a policy statement from the American Association for Cancer Research and the American Society of Clinical Oncology.

73 : Electronic cigarettes: a policy statement from the American Heart Association.

74 : Electronic Cigarettes: A Primer for Clinicians.

75 : Electronic Cigarettes: A Primer for Clinicians.

76 : Electronic Cigarettes: A Primer for Clinicians.

77 : Electronic Cigarettes: A Primer for Clinicians.

78 : Electronic Cigarettes: A Primer for Clinicians.

79 : E-cigarettes: Impact of E-Liquid Components and Device Characteristics on Nicotine Exposure.

80 : Evaluating nicotine levels selection and patterns of electronic cigarette use in a group of "vapers" who had achieved complete substitution of smoking.

81 : Nicotine, Carcinogen, and Toxin Exposure in Long-Term E-Cigarette and Nicotine Replacement Therapy Users: A Cross-sectional Study.

82 : Nicotine delivery, retention and pharmacokinetics from various electronic cigarettes.

83 : Electronic cigarettes and nicotine clinical pharmacology.

84 : Nicotine levels in electronic cigarettes.

85 : Nicotine levels in electronic cigarettes.

86 : Evaluation of Bronchoalveolar Lavage Fluid from Patients in an Outbreak of E-cigarette, or Vaping, Product Use-Associated Lung Injury - 10 States, August-October 2019.

87 : Characteristics of Hospitalized and Nonhospitalized Patients in a Nationwide Outbreak of E-cigarette, or Vaping, Product Use-Associated Lung Injury - United States, November 2019.

88 : Update: Characteristics of a Nationwide Outbreak of E-cigarette, or Vaping, Product Use-Associated Lung Injury - United States, August 2019-January 2020.

89 : Hospitalizations and Deaths Associated with EVALI.

90 : Hospitalizations and Deaths Associated with EVALI.

91 : Promise and peril of e-cigarettes: can disruptive technology make cigarettes obsolete?

92 : Carbonyl compounds in electronic cigarette vapors: effects of nicotine solvent and battery output voltage.

93 : Mechanisms of propylene glycol and triacetin pyrolysis.

94 : Hidden formaldehyde in e-cigarette aerosols.

95 : Cardiovascular effects of electronic cigarettes.

96 : Increased Cardiac Sympathetic Activity and Oxidative Stress in Habitual Electronic Cigarette Users: Implications for Cardiovascular Risk.

97 : Sympathomimetic Effects of Acute E-Cigarette Use: Role of Nicotine and Non-Nicotine Constituents.

98 : Cardiovascular Effects of Switching From Tobacco Cigarettes to Electronic Cigarettes.

99 : Prospective study of e-cigarette use and respiratory symptoms in adolescents and young adults.

100 : Electronic Cigarette Use and Respiratory Symptoms in Chinese Adolescents in Hong Kong.

101 : Electronic Cigarette Use and Respiratory Symptoms in Adolescents.

102 : Electronic Cigarette Use and Chronic Respiratory Symptoms among U.S. Adults.

103 : Association of smoking and electronic cigarette use with wheezing and related respiratory symptoms in adults: cross-sectional results from the Population Assessment of Tobacco and Health (PATH) study, wave 2.

104 : Flavorings in electronic cigarettes: an unrecognized respiratory health hazard?

105 : Evaluation of electronic cigarette liquids and aerosol for the presence of selected inhalation toxins.

106 : Identification of toxicants in cinnamon-flavored electronic cigarette refill fluids.

107 : Identification of Cytotoxic Flavor Chemicals in Top-Selling Electronic Cigarette Refill Fluids.

108 : Comparison of the cytotoxic potential of cigarette smoke and electronic cigarette vapour extract on cultured myocardial cells.

109 : Comparison of electronic cigarette refill fluid cytotoxicity using embryonic and adult models.

110 : Flavoring Chemicals in E-Cigarettes: Diacetyl, 2,3-Pentanedione, and Acetoin in a Sample of 51 Products, Including Fruit-, Candy-, and Cocktail-Flavored E-Cigarettes.

111 : Cherry-flavoured electronic cigarettes expose users to the inhalation irritant, benzaldehyde.

112 : Balancing the Benefits and Harms of E-Cigarettes: A National Academies of Science, Engineering, and Medicine Report.

113 : Burns from e-cigarettes and other electronic nicotine delivery systems.

114 : Explosion Injuries from E-Cigarettes.

115 : Burns injuries from e-cigarettes kept in pockets.

116 : Electronic cigarette explosion/burn and poisoning related emergency department visits, 2018-2019.

117 : Alarming increase in electronic nicotine delivery systems-related burn injuries: A serious unregulated public health issue.

118 : England Is Handing out E-Cigarettes: Is the "Swap to Stop" Tobacco Control Scheme Harm Reduction or Harm Production?

119 : Association of Electronic Cigarette Use With Initiation of Combustible Tobacco Product Smoking in Early Adolescence.

120 : Progression to Traditional Cigarette Smoking After Electronic Cigarette Use Among US Adolescents and Young Adults.

121 : E-Cigarettes and Future Cigarette Use.

122 : Association Between Initial Use of e-Cigarettes and Subsequent Cigarette Smoking Among Adolescents and Young Adults: A Systematic Review and Meta-analysis.

123 : Electronic Cigarettes as an Introductory Tobacco Product Among Eighth and 11th Grade Tobacco Users - Oregon, 2015.

124 : Gateway or common liability? A systematic review and meta-analysis of studies of adolescent e-cigarette use and future smoking initiation.

125 : Errors in Data Input in Meta-analysis on Association Between Initial Use of e-Cigarettes and Subsequent Cigarette Smoking Among Adolescents and Young Adults.

126 : E-cigarettes and National Adolescent Cigarette Use: 2004-2014.

127 : Short-term pulmonary effects of using an electronic cigarette: impact on respiratory flow resistance, impedance, and exhaled nitric oxide.

128 : Association Between Youth Smoking, Electronic Cigarette Use, and COVID-19.

129 : Electronic Nicotine Delivery Systems.

130 : Public Policy to Protect Children From Tobacco, Nicotine, and Tobacco Smoke.

131 : Potential Solutions to Electronic Cigarette Use Among Adolescents.

132 : "Smoking revolution": a content analysis of electronic cigarette retail websites.

133 : Beliefs and experimentation with electronic cigarettes: a prospective analysis among young adults.

134 : E-cigarette Marketing Exposure and Subsequent Experimentation Among Youth and Young Adults.

135 : E-Cigarette Marketing Exposure Is Associated With E-Cigarette Use Among US Youth.

136 : E-cigarettes, vaping, and youth.

137 : E-cigarettes and the future of tobacco control.

138 : The renormalization of smoking? E-cigarettes and the tobacco "endgame".

139 : Electronic cigarettes: an evaluation of exposure to chemicals and fine particulate matter (PM).

140 : Peering through the mist: systematic review of what the chemistry of contaminants in electronic cigarettes tells us about health risks.

141 : Does e-cigarette consumption cause passive vaping?

142 : Acute effects of using an electronic nicotine-delivery device (electronic cigarette) on myocardial function: comparison with the effects of regular cigarettes.

143 : Acute effects of using an electronic nicotine-delivery device (electronic cigarette) on myocardial function: comparison with the effects of regular cigarettes.

144 : Electronic nicotine delivery systems: executive summary of a policy position paper from the American College of Physicians.

145 : Differential Taxes for Differential Risks--Toward Reduced Harm from Nicotine-Yielding Products.

146 : Regulation of electronic cigarettes.

147 : WHO review exaggerated dangers of e-cigarettes, say specialists.

148 : WHO review exaggerated dangers of e-cigarettes, say specialists.

149 : Nicotine without smoke-putting electronic cigarettes in context.

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