Expected urine drug screening results and common substances that can cause false positives^[1-4]

Substance tested	Time of detection	Expected positive IAS (presumptive) testing	Expected positive result with confirmatory (definitive) testing	False positives with IAS	Comments
Codeine	1 to 3 days	Opioids	Codeine Morphine Possibly hydrocodone* Dihydrocodeine	Poppy seeds^¶ Quinolone antibiotics Rifampin Papaverine Verapamil Diphenhydramine Dextromethorphan Quinine Naloxone Nalmefene
Morphine	1 to 3 days	Opioids	Morphine Possibly hydromorphone*	Poppy seeds^¶ Quinolones Rifampin Papaverine Verapamil Diphenhydramine Dextromethorphan Quinine Naloxone Nalmefene
Hydrocodone	1 to 3 days	Possibly opioids^Δ	Hydrocodone Possibly hydromorphone Norhydrocodone	Poppy seeds Quinolone antibiotics Rifampin Papaverine Verapamil Diphenhydramine Quinine Naloxone Nalmefene
Hydromorphone	1 to 3 days	Possibly opioids^Δ	Hydromorphone	Poppy seeds Quinolone antibiotics Rifampin Papaverine Verapamil Diphenhydramine Quinine Naloxone Nalmefene
Oxycodone	1 to 3 days	Possibly opioids^Δ Oxycodone IAS^Δ	Oxycodone Possibly oxymorphone Noroxycodone	Poppy seeds Quinolone antibiotics Rifampin Papaverine Verapamil Diphenhydramine Quinine Naloxone Nalmefene
Oxymorphone	1 to 3 days	Possibly opioids^Δ Oxycodone IAS^Δ	Oxymorphone Noroxymorphone	Poppy seeds Quinolone antibiotics Rifampin Papaverine Verapamil Diphenhydramine Quinine Maloxone Nalmefene
Fentanyl	1 to 3 days	N/A	Fentanyl Norfentanyl
Meperidine	1 to 3 days	N/A	Normeperidine Possibly meperidine
Methadone	3 to 7 days	Methadone IAS^◊	Methadone and EDDP	Diphenhydramine Chlomipramine Quetiapine
Buprenorphine	Up to 11 days	Buprenorphine IAS^◊	Buprenorphine Norbuprenorphine	Codeine Morphine Tramadol Methadone Amisulpride^§ Sulpiride^§
Heroin	Low dose (3 mg IV): <1/2 day High dose (6 to 12 mg IV): 1 to 2 days	Opiates	6-monoacetyl morphine Morphine
Tramadol	2 to 4 days	N/A	Tramadol Nortramadol
Amphetamines	2 to 3 days	Amphetamines	Amphetamine Metamphetamine MDMA	Amantadine Chlorpromazine Desipramine Fluoxetine Labetolol Selegiline Phentermine Trazodone Buproprion Phenylephrine Pseudoephedrine
Cocaine (This includes illegitimate use, including coca leaf tea, and legitimate medical use of topical anesthetics containing cocaine)	2 to 4 days, up to 8 days with heavy use	Cocaine	Cocaine
Marijuana	2 to 4 days, up to 30 days with chronic use	Cannabinoids	THC	Pantoprazole Hemp seed Efafirenz Dronabinol^¥ Nabiximols^¥	Visine eye drops (placed directly in the urine) can cause false negative testing for some IAS assays Synthetic cannabinoids are not reliably detected
Benzodiazepines	1 to 3 days short acting Up to 30 days with long acting	Benzodiazepine IAS	Specific drug	Oxaprozin Sertraline	IAS for benzodiazepines has high false negative, variable cross-reactivity, and poor sensitivity for some drugs
Phencyclidine	Casual use: 2 to 7 days Chronic use: up to 30 days	Phencyclidine	Phencyclidine	Dextromethorphan Diphenhydramine Tramadol Doxylamine Ibuprofen Imipramine Meperidine Thioridazine Venlafaxine Desmethylvenlafaxine
Alcohol	Up to 8 hours^‡	N/A	Alcohol Ethyl glucuronide Ethyl sulfate	Cough syrup Mouthwash Use of hand sanitizers Nonalcoholic beer or wine Communion wine Food cooked with alcohol	Ingestion or use of alcohol containing substances may cause true positive test result, but may not indicate clinically relevant ingestion of alcoholic beverages

This table shows the expected results for immunoassay and confirmatory testing. The likelihood of false positive results depends on the cutoff levels used for the test. Unexpected results should be discussed with the patient, and if uncertain, the laboratory technician or the test manufacturer (for point-of-care tests).

IAS: immunoassay screen; EDDP: 2-ethylidene-1,5-dimethyl-3,3-diphenylpyrrolidine; N/A: not applicable; IV: intravenous; MDMA: 3,4-methylenedioxymethamphetamine; THC: tetrahydrocannabinol.
* Only very low levels of the metabolite appears in the urine.
¶ Ingestion of poppy seeds can cause a false positive for codeine or morphine with definitive testing.
Δ Standard immunoassay opiate screens do not reliably detect semisynthetic opioids (ie, hydromorphone, hydrocodone, oxycodone, oxymorphone) and do not detect synthetic opioids (fentanyl, meperidine, methadone, buprenorphine).
◊ Expanded IAS panels may include oxycodone, methadone, buprenorphine, benzodiazepines, and barbiturates.
§ Drug not available in the United States.
¥ Positive test result represents true positive for THC.
‡ Testing for ethyl glucuronide or ethyl sulfate can identify alcohol use for up to 80 hours after ingestion.

References:

Interagency Guideline on Prescribing Opioids for Pain. Washington State Agency Medical Directors' Group. Available at: https://agencymeddirectors.wa.gov/Files/2015AMDGOpioidGuideline.pdf (Accessed on December 12, 2021).
Verstraetem AG, Detection times of drugs of abuse in blood, urine, and oral fluid. Ther Drug Monit 2004; 26:200.
Reisfield GM, Salazar E, Bertholf RL. Rational use and interpretation of urine drug testing in chronic opioid therapy. Ann Clin Lab Sci 2007; 37:30.
Saitman A, Park HD, Fitzgerald RL. False-positive interferences of common urine drug screen immunoassays: a review. J Anal Toxicol 2014; 38:387.

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Expected urine drug screening results and common substances that can cause false positives[1-4]

Expected urine drug screening results and common substances that can cause false positives^[1-4]