Patient education: Using an epinephrine autoinjector (Beyond the Basics)

INTRODUCTION — Allergic reactions can be caused by foods, medications, exercise, latex, insect stings, or unknown triggers. These triggers can cause a sudden, potentially life-threatening allergic reaction called anaphylaxis in people who are allergic to them. Anaphylaxis is treated with a medication called epinephrine. If you have a known serious allergy, your health care provider will develop a treatment plan so you and your family know what to do if you have an allergic reaction.

This article discusses the role of epinephrine in treating anaphylaxis, including details about how and when to use your autoinjector device. More information about the symptoms, diagnosis, and treatment of anaphylaxis is available separately. (See "Patient education: Anaphylaxis symptoms and diagnosis (Beyond the Basics)" and "Patient education: Anaphylaxis treatment and prevention of recurrences (Beyond the Basics)".)

WHAT IS AN AUTOINJECTOR? — An autoinjector is a device that contains medication and allows you to give yourself (or someone else) a dose when immediate treatment is needed. There are different brands of epinephrine autoinjector; the one your health care provider prescribes will depend on availability as well as your insurance coverage. While different devices may work slightly differently, they are all similar in that they use a needle to inject the medication, and they are each intended for a single use (and then must be disposed of).

PATIENT AND FAMILY EDUCATION — Any person with allergies (or their caregivers) should learn to use an epinephrine autoinjector before it is needed. It's also important that other people are aware of the person's allergy and familiar with how to use an autoinjector. This includes anyone who spends significant time with the person, including family members, caregivers, teachers, friends, and coworkers. Anaphylaxis is unpredictable, and while a person may have a mild reaction to an allergen one time, a serious or even life-threatening reaction can occur another time. When an allergic reaction happens, people might panic; knowing where the autoinjector is and how to use it is critical in this situation. In addition, a quick response is necessary to prevent serious complications of anaphylaxis.

If you are prescribed an epinephrine autoinjector, fill the prescription promptly so you have the medication on hand. People who are at risk of anaphylaxis should keep at least one epinephrine autoinjector with them at all times. Most allergy specialists recommend having at least two doses of epinephrine available, and some prescribe more. The reason for this is that more than one dose of epinephrine may be needed to treat a more severe anaphylactic reaction or a second wave of symptoms. If you think you need more autoinjectors than you have (for example, to store extras at school or work, or with caregivers), let your health care provider know.

Practicing using your autoinjector — Once you have your autoinjector, it's important to practice using it so you are comfortable with the steps involved. This will help you be prepared to use it if and when you need to. Many autoinjectors come with a practice device (that does not have a needle or actual medicine) that you can use to practice. You can also find videos online showing how each device is used. It's important to review this information regularly.

Carrying and storing your autoinjector — It's important to make sure to always have an autoinjector available, including at school or work, when attending parties or traveling, during exercise, and while dining out. It should be kept in a place that can be easily located by others in an emergency, and family and friends should be informed about where the autoinjector is stored. It is also important to ensure that the autoinjector is not expired, although an expired autoinjector may be used if there is no alternative.

Epinephrine should be stored at normal room temperature, away from extreme cold and heat; you should not store your autoinjector in a car. Epinephrine autoinjectors are unlikely to be damaged by X-ray equipment at airport security.

Expiration and efficacy — The epinephrine cartridge window should be examined periodically to ensure that the solution is colorless and contains no floating particles. If the solution is discolored or contains particles, the concentration of epinephrine will be lower and the autoinjector should be replaced with a new one. Each autoinjector will be marked with the month and year it expires. Be sure to check this date regularly so you know when yours will expire. If there is an emergency and you only have access to an expired autoinjector, using this is preferable to not giving treatment at all, even if the solution inside has started to discolor. Expired autoinjectors may still have some amount of active epinephrine. However, this is not ideal, and it's best to ensure that you have a current autoinjector available at all times.

THE ROLE OF EPINEPHRINE IN TREATING ANAPHYLAXIS — Epinephrine is the best treatment for anaphylaxis, and it works best if it is given within the first few minutes of a severe allergic reaction. Epinephrine is the same as adrenaline (the hormone that the body produces in stressful or emotional situations). It rapidly treats all of the most dangerous symptoms of anaphylaxis, including throat swelling, difficulty breathing, and low blood pressure. However, epinephrine is not a perfect treatment, so avoiding anything that might trigger a reaction is still a critical part of managing an allergy.

Other medications are also used in the treatment of allergic reactions and can help with some of the symptoms, but only epinephrine treats the entire reaction. Antihistamines such as cetirizine (sample brand name Zyrtec) or diphenhydramine (sample brand name Benadryl) help with itching and hives, and asthma inhalers (such as albuterol) can help with coughing and wheezing. However, these medications do not treat the dangerous symptoms of throat swelling and low blood pressure, and they are not substitutes for epinephrine. In addition, antihistamines taken by mouth are too slow-acting to be effective in a rapidly developing episode of anaphylaxis. In contrast, injected epinephrine works within a few minutes.

WHEN TO USE AN EPINEPHRINE AUTOINJECTOR — Your doctor will give you an "action plan" with specific instructions about when to inject epinephrine; it's important to review and discuss this ahead of time so you know what to do in the event of an allergic reaction. The symptoms of anaphylaxis are discussed in detail separately. (See "Patient education: Anaphylaxis symptoms and diagnosis (Beyond the Basics)".)

A person who is having an allergic reaction should use their epinephrine autoinjector immediately if they:

●Are having trouble breathing

●Feel tightness in the throat

●Feel lightheaded or thinks they might pass out

The autoinjector should also be used promptly after an allergen exposure if the person has symptoms that could progress to the life-threatening ones listed above. These may include wheezing, repetitive coughing, swelling of the lips, tongue, or throat, spreading hives, repeated vomiting (especially with other symptoms), having a "feeling of doom," or a combination of these symptoms. For milder symptoms like a few hives, mild abdominal discomfort, or itching, your allergist may tell you to give another medication (eg, an antihistamine) first. The most important thing is to become familiar with your (or your child's) allergy action plan so you can act quickly in the event of an allergic reaction.

If treating a child with an allergic reaction, you should also use the autoinjector if the child:

●Is not responding, seems groggy, or passes out during an allergic reaction.

●Has food allergies and is vomiting repeatedly shortly after eating, especially if these symptoms are accompanied by flushing or hives.

●Is coughing repeatedly during an allergic reaction.

●Has had anaphylaxis before and develops many spreading hives after possibly eating a trigger food.

●Has definitely eaten a trigger food that previously caused very severe anaphylaxis and has any symptoms at all, even mild symptoms.

HOW TO USE AN EPINEPHRINE AUTOINJECTOR — The exact steps to follow depend on which autoinjector you are prescribed. Any time you get a new device (or refill a prescription), you should review the instructions that come with the autoinjector. This is important as the instructions may change slightly or you may receive a different device than you have had in the past (for example, if your health care provider switches you from a brand name to a generic version).

It is also a good idea to watch videos or review pictures showing how to use your (or your child's) autoinjector. This will help you understand how to prepare the device (including releasing the safety cap), the angle to use for giving the injection, how to actually release the medication, and how long to hold the device in place. Although some manufacturers suggest "swinging" the device, be cautious because doing this can increase the chances of missing the intended location or twisting the device.

If possible, stay with other people when you use an autoinjector on yourself or someone else, in case you need help. Epinephrine is injected into the upper outer thigh (picture 1). There is no need to undress, because the injector works through clothing. However, if there is a possibility of hitting a buckle, zipper, or contents of the pockets, you can lift the edge of a skirt or pull down the pants partway.

Several available epinephrine autoinjectors are discussed briefly in the sections that follow.

EpiPen or EpiPen Jr — These epinephrine autoinjectors contain one dose per autoinjector. They are available in two different doses based on the person's weight; one (brand name EpiPen) contains 0.3 mg of epinephrine and is intended for older children and adults, and the other (brand name EpiPen Jr) contains 0.15 mg of epinephrine and is intended for use in young children.

The EpiPen is available in packages of two, in case a second dose is needed. Large-sized adults may need to repeat the dose. A second dose may also be needed if symptoms are not improving or getting worse after about five minutes, or if symptoms come back before reaching the emergency department.

There are also generic versions of EpiPen available. These work the same as the brand-name version. When you fill a prescription, be sure to look at the device and the instructions that come with it, as they can vary slightly. (See 'Generic epinephrine' below.)

Auvi-Q — Auvi-Q (or the Canadian version Allerject) epinephrine autoinjectors contain one dose per autoinjector. They are rectangular, about the size of a cell phone, and play a recording that explains each step in the self-injecting process. Auvi-Q autoinjectors come in three different doses: one intended for adults and older children, one intended for young children, and a third for use in infants and toddlers.

Generic epinephrine — There are several generic versions of epinephrine autoinjectors available. These may be a lower-cost alternative to brand-name devices, and they contain the same medication. They may be shaped and activated differently from the brand-name devices described above. Be sure to inspect the device that you receive and learn how to activate it. Online videos are available. Talk to your health care provider or pharmacy if you are not sure which device you have or if you want to know more about your options. (See 'Cost concerns' below.)

Other devices — Other devices (such as the Emerade and Jext autoinjectors) may be available around the world, including some with doses higher than those available in the United States. A prefilled syringe that is not an autoinjector is also available (brand name Symjepi). Whatever device you get, it's important to review how to use it by using a practice device (to practice without actually giving a dose of epinephrine), reading the directions, and watching a manufacturer video (available online). (See 'Practicing using your autoinjector' above.)

WHAT TO DO AFTER USING THE AUTOINJECTOR — After using an autoinjector to treat an allergic reaction or anaphylaxis, it is important to immediately seek emergency care. While epinephrine itself does not cause problems, an allergic reaction sometimes improves after treatment with epinephrine but then symptoms come back. In the emergency department, you will be monitored closely for several hours so the staff can treat you again quickly if needed.

When possible, ask someone else to call for help (in the United States and Canada, call 9-1-1 for an ambulance). If you are alone, inject yourself with the autoinjector first and then call or go for help.

If you have used an autoinjector to treat an allergic reaction in someone else and they begin to feel weak or dizzy, have them lie down and elevate their knees or feet. If the person feels faint or has fainted, leave them in the lying down position. Never prop them up, because this can prevent blood from reaching the heart and brain.

Side effects of epinephrine — The benefits of epinephrine are far greater than the risk of side effects. However, epinephrine can cause short-lived side effects in some patients. The most common side effects include the following:

●Heart – Fast and/or pounding heartbeat, temporary chest pain

●Nervous system – Nervousness, trembling, feeling cold, anxiety, headache, dizziness

●Digestive system – Nausea, dry throat

●Lungs – Temporary shortness of breath

The thigh might also be sore where you injected the medication.

Autoinjector disposal — After you have used an autoinjector, it no longer contains medication and cannot be used again. However, you should not throw it away in the regular trash. Instead, you can take used or expired autoinjectors (inside the case) to a hospital or health care provider for proper disposal. Sometimes, local police station or fire departments also have containers for disposing of sharp objects and/or medications.

FOLLOW-UP CARE — People have varying responses to a severe allergic reaction. Some people have symptoms that will resolve rapidly and completely with treatment. They may feel tired but otherwise normal afterward. Other people have symptoms that take longer to resolve. For most people, facial swelling and breathing symptoms resolve completely after 24 to 48 hours.

Some people experience a second reaction after the initial allergic reaction, although this is not common. Second reactions can occur hours to one day later, although most second reactions happen within eight hours. This is why it is so important to stay at the emergency department for several hours of observation after a reaction. (See 'What to do after using the autoinjector' above.)

A health care provider may prescribe additional medications for treatment after a reaction, such as antihistamines or oral glucocorticoids (eg, prednisone). It is possible, although not proven, that these medications can help to prevent a second reaction from happening.

COST CONCERNS — If your autoinjectors are very expensive, ask your doctor or nurse whether there might be other options. You may be able to save money by switching from a brand name to a generic version (see 'Generic epinephrine' above). Some manufacturers also offer cost-saving coupons online.

WHERE TO GET MORE INFORMATION — Your health care provider is the best source of information for questions and concerns related to your medical problem.

This article will be updated as needed on our website (www.uptodate.com/patients). Related topics for patients, as well as selected articles written for health care professionals, are also available. Some of the most relevant are listed below.

Patient level information — UpToDate offers two types of patient education materials.

The Basics — The Basics patient education pieces 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.

Patient education: How to use an epinephrine autoinjector (The Basics)
Patient education: Anaphylaxis (The Basics)
Patient education: Angioedema (The Basics)
Patient education: Insect allergy (The Basics)
Patient education: Allergy skin testing (The Basics)
Patient education: Peanut, tree nut, and seed allergy (The Basics)
Patient education: Drug allergy (The Basics)
Patient education: Allergy shots (The Basics)

Beyond the Basics — Beyond the Basics patient education pieces are longer, more sophisticated, and more detailed. These articles are best for patients who want in-depth information and are comfortable with some medical jargon.

Patient education: Anaphylaxis symptoms and diagnosis (Beyond the Basics)

Professional level information — Professional level articles are designed to keep doctors and other health professionals up-to-date on the latest medical findings. These articles are thorough, long, and complex, and they contain multiple references to the research on which they are based. Professional level articles are best for people who are comfortable with a lot of medical terminology and who want to read the same materials their doctors are reading.

Anaphylaxis: Emergency treatment
Bee, yellow jacket, wasp, and other Hymenoptera stings: Reaction types and acute management
Hereditary angioedema: Epidemiology, clinical manifestations, exacerbating factors, and prognosis
Clinical manifestations of food allergy: An overview
Diagnosis of Hymenoptera venom allergy
Diagnostic evaluation of IgE-mediated food allergy
Drug eruptions
Fatal anaphylaxis
Food allergy in schools and camps
Food-induced anaphylaxis
History and physical examination in the patient with possible food allergy
Laboratory tests to support the clinical diagnosis of anaphylaxis
Pathophysiology of anaphylaxis
Prescribing epinephrine for anaphylaxis self-treatment
Hereditary angioedema: Acute treatment of angioedema attacks
Anaphylaxis in infants

The following organizations also provide reliable health information.

●Food Allergy Research & Education (FARE) (www.foodallergy.org/)

●American Academy of Allergy, Asthma & Immunology (AAAAI) (www.aaaai.org/)

●American College of Allergy, Asthma & Immunology (ACAAI) (acaai.org/)

●Food Allergy Canada (foodallergycanada.ca/)

●Anaphylaxis Campaign (www.anaphylaxis.org.uk/)

●American Academy of Pediatrics (AAP) (www.aap.org/)

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