How can you fail a drug test without doing drugs? Lots of ways! Everyone knows about poppy seeds tripping you up, but did you know that pizza, baby soap, ibuprofen and other unsuspecting things can do that too?

Head looked at what drug-testing laboratories, drug rehab centers and government agencies had to say about what can cause you to mistakenly test positive for drugs. Our research uncovered foods, household items, and prescription and over-the-counter medicines that can trigger a false positive. If you’ve been consuming or using these things and anticipate scheduled or random drug testing, read our findings on how best – and safest – to rid your body of misleading trace substances. As always, consult your physician first though.

Drug Testing 101

Drug testing is the targeted evaluation of a sample of your urine, blood, saliva, hair and/or sweat to determine whether you’ve been using (or, in the case of prescription medications, misusing) specific drugs. This testing is done for:

  • Employment (e.g., conditional job offers, random screening, workplace accidents)
  • Sports (performance enhancers)
  • Substance abuse programs (monitoring progress and/or abstinence)
  • Legal proceedings (e.g., evidence in a court case, accident investigations)
  • Medicinal control (e.g., ensuring the proper short-term use of an addictive pain reliever)

The process begins with the collection of a biological specimen, such as urine or blood. After it has been collected, that specimen is typically divided in half: one half for testing, and the other half on reserve in case the test is contaminated and must be redone, or in case secondary (i.e., confirmatory) testing is necessary.

Photo by Artem Podrez/

Photo by Artem Podrez/

Testing usually consists of five or 10 panels, meaning that either five or 10 substances in particular are the subject of the analysis. The most common substances are:

  • Alcohol
  • Marijuana (specifically: delta-9-tetrahydrocannabinol [THC])
  • Cocaine
  • Phencyclidine (PCP)
  • Opiates (e.g., codeine, morphine, oxycodone)
  • (Meth)amphetamines
  • 3,4-Methyl​enedioxy​methamphetamine (aka ecstasy, molly, mandy)
  • Narcotic prescription drugs (e.g., methadone)
  • Barbiturates (e.g., phenobarbital)
  • Methaqualone (aka Quaaludes)
  • Propoxyphene (aka Darvon)
  • Benzodiazepines (e.g., Valium, Xanax)

Urine and saliva tests provide insight into recent substance use and impairment, and hair tests enable the detection of substance use over an extended period. Blood tests offer the greatest precision and detail, and can do so immediately. By contrast, urine and saliva tests can take up to four hours to deliver results and up to three days for follow-on confirmatory testing.

Photo by Curtis Adams/

Photo by Curtis Adams/

The types of techniques used in testing are:

  • Immunoassay, which uses antibodies to identify the presence of substances.
  • Gas chromatography (GC-MS), which separates and analyzes compounds.
  • Mass spectrometry, which measures the precise molecular mass of ions.
  • High-performance liquid chromatography (HPLC), which enables the separation, identification and quantification of individual components.

Immunoassay tests are the most common, and GC-MS and HPLC tests are usually used in secondary (i.e., confirmatory) testing when someone challenges a test’s results.

False Positives

When a drug test detects a substance that isn’t actually there, you have what’s known as a false positive. This occurs when the test results derive from imposter substances whose metabolic forms match or closely resemble the metabolic forms of the drug(s) in question. The following are the imposters that drug-testing laboratories, drug rehab centers (which frequently test patients) and government agencies (the strictest drug-testers) observe.

Foods and Beverages That Can Cause a False Positive

Consult the Sources and Suggested Reading section for extensive details on how each of the following (and many not listed here) can cause false positives. Those discussed in detail in this article are marked with an asterisk (*).

  • Alcohol-infused foods*
  • Caffeinated beverages*
  • Coca tea
  • Durian (Asian fruit)
  • Granola containing poppy seeds and/or hemp seeds
  • Hemp seeds*
  • Pizza*
  • Poppy seeds*
  • Seafood*
  • Serotonin-loaded foods (e.g., avocados, bananas, citrus fruits, nuts)
  • Tonic water with quinine

Alcohol-Infused Foods

The firm Sivertson & Barrette Law identified foods that interfere with drug testing for alcohol. Some are desserts, and some are dishes that are cooked with alcohol that can fail to burn off in the cooking process.

  • Bourbon cake
  • Brandy custard
  • Gin-spiked tarts
  • Rum cake
  • Vodka tiramisu
  • Chocolate and brandy truffles
  • Champagne chocolates
  • Single-malt caramels
  • Chicken cacciatore (cooked with white wine)
  • Tequila lime shrimp
  • Chicken marsala
  • Coq au vin
  • Boeuf bourguignon
  • Beer bread
  • Bratwurst boiled in beer
  • Maple bourbon glaze on pork chops
  • Margarita guacamole

The firm also reminded readers/prospective clients that names of alcohol aren’t always as obvious as “vodka” and “margarita” when you’re not a connoisseur, such as:

  • Negroni (a gin)
  • Vermouth (a cocktail)
  • Prosecco (a wine)
  • Campari (a liqueur)
  • Amaretto (a liqueur)

So, ask the server about words you don’t recognize, especially in names of desserts. Also, be mindful that vanilla extract contains ethanol, a type of alcohol that will make you test positive.

Rum Cake with White Chocolate Ganache and Berries/ Photo by Karina Kungla /

Rum Cake with White Chocolate Ganache and Berries/ Photo by Karina Kungla /

Caffeinated Beverages

Coffee and tea can appear in a drug test as metanephrine, a substance indicating drug/alcohol withdrawal. ARCpoint Labs recommends avoiding coffee and tea for at least 72 hours before an alcohol and/or drug test.

Hemp Seeds

Cannabis is divided into “marijuana” and “hemp” by legislators, but nature makes no such distinction. So, in the legal framework in the United States, hemp is any form of cannabis with a THC concentration of less than 0.3%, typically referring to the cannabis sativa subspecies. This is because amounts that low are insufficient to cause intoxication – unless, of course, they build up in your system and breach the barrier.

THC is stored in your body’s fat cells, where it can remain for up to five weeks. So, if you keep adding 0.3% to whatever percentage of THC is still there in your cells, at some point, it will look like you were high on THC. That’s what the test will conclude anyhow. With a urine test (the most commonly used form), if you have more than 50 nanograms of THC per milliliter of urine (ng/mL), you’ll test positive for THC.


Although pizza can’t get you drunk (or can it?), it can certainly make you appear drunk in a saliva or breathalyzer test. This is because it’s rich in yeast, the ingredient that makes the pizza dough rise. Yeast ferments sugar into alcohol (ethanol specifically), and that alcohol gradually builds up in your mouth while you’re eating. Eventually, the amount gets you over the blood-alcohol-level threshold, even though you’re not intoxicated. 

Of note, that same yeast can even show up in a drug test as THC, according to drug-testing laboratories ReliaLab Test and USA Mobile Drug Testing. In fact, both laboratories recommend that you avoid pizza and any other yeast-rich food (e.g., bread, ripe fruits) for a couple of days before your drug test.

Photo by Eneida Nieves /

Photo by Eneida Nieves /

Poppy Seeds

Poppy seeds themselves don’t contain opiates, but they can become contaminated with opiates in the milky latex of the seed pod covering them during processing. Consequently, they contain trace amounts (0.5 to 10 micrograms per gram) of codeine and morphine in their natural state. This is far below the concentration (5,000 to 30,000 micrograms per gram) in prescribed opiates, but it’s enough to make you fail your drug test. Those imposter substances will show up in a drug test within two hours of consuming poppy seeds, and will still show up even 48 or more (up to 60) hours later. So, avoid consuming these for at least two days before a drug test.

Common knowledge of the poppy seed false positive has led many employers to search for needle marks or something to corroborate a positive test, rather than assuming the worst. Going beyond that, federal authorities (specifically, the U.S. Department of Transportation) raised the required codeine/morphine cutoff concentration from 300 to 2,000 ng/mL (in urine) for the same reason. Despite that, the U.S. Department of Defense maintains a harder stance and expressly prohibits poppy seed consumption among the armed forces.

It’s easy to avoid poppy seed muffins and lemon poppy seed cake, but here are some other things that you might forget contain poppy seeds because they’re not included in the name:

  • Bagels (especially everything bagels), buns and rolls
  • Salads and salad dressings
  • Fillings in desserts
  • Babka
  • Granola

In addition, be careful with poppy-seed-derived teas, sleep aids and pain relievers. Whereas poppy seeds used in baking are rigorously washed and regulated, the poppy seeds in the latter products are neither washed nor regulated. In fact, they’re intentionally unwashed so that they’ll hang on to the opiates. According to the Drug Enforcement Administration, poppy seed tea contains sufficient amounts of alkaloids to produce psychoactive effects and caused 12 lethal overdoses. (Note: That number has likely risen since November 2019, when that report was published.)


Heavy metals, such as mercury, lead, arsenic (organic, not the deadly kind) and cadmium, are naturally present in seafood (e.g., fin-fish, crabs, mollusks, shrimp) owing to the metals’ presence in the environment. Shellfish build up cadmium and arsenic in your body, and predatory fish (e.g., swordfish, bigeye tuna) build up mercury in your body. These substances will trigger a false positive in your drug test up to two days after you’ve eaten them.

Photo by Farhad Ibrahimzade/

Photo by Farhad Ibrahimzade/

Medications That Can Cause a False Positive

Consult the Sources and Suggested Reading section for extensive details on how each of the following (and many not listed here) can cause false positives.

  • Acetaminophen (e.g., Tylenol)
  • Allergy medicines with pseudoephedrine (e.g., Allegra-D, Clarinex-D, Mucinex-D)
  • Analgesics
  • Antibiotics (specifically: fluoroquinolones, rifampin, and the quinolones levofloxacin and ofloxacin)
  • Antidepressants (e.g., quetiapine/Seroquel, sertraline/Zoloft, trazodone, Amitril, Norpramin, Zonalon, Prudoxin, Tofranil, venlafaxine/Effexor XR, Wellbutrin, Prozac, Desyrel)
  • Antihistamines (e.g., levomethamphetamine in inhalers, brompheniramine, Zyrtec, Allegra, Benadryl, Claritin)
  • Anti-nausea medicines (e.g., phenothiazines, Promethazine)
  • Antipsychotics (e.g., quetiapine, chlorpromazine, Seroquel)
  • Antiretrovirals (e.g., Sustiva)
  • Aspirins (e.g., Excedrin)
  • Attention Deficit Hyperactivity Disorder (ADHD) medicines (e.g., Ritalin)
  • Beta blockers (e.g., Trandate)
  • Cannabidiol (CBD) (Explained after the list.)
  • Cold/flu medicines (e.g., Dimetapp, NyQuil, Robitussin)
  • Decongestants (e.g., Mucinex, Sudafed, Vicks inhaler)
  • Glucocorticoids (specifically: prednisone)
  • Hypertension medicines (e.g., Cardizem/Diltiazem)
  • Ibuprofen (e.g., Advil, Motrin)
  • Metformin (diabetes treatment)
  • Naproxen sodium (e.g., Aleve Arthritis)
  • Proton-pump inhibitors (e.g., omeprazole, esomeprazole, pantoprazole)
  • Sleep aids (e.g., diphenhydramine, ZzzQuil, Unisom, Nytol, Advil PM)
  • Vitamin B supplements from hemp-seed oil
  • Weight-loss pills (e.g., phentermine, Adipex-P)

Pure, hemp-derived CBD contains no THC and has not been found to cause a false positive. However, the purity of CBD products has yet to be regulated, so you can’t rely on your routine CBD products to be safe for drug testing. (For better advice than that, read “CBD & Drug Testing: Your Questions Answered” from DNA Legal.) As Banner Health observes, some CBD products contain amounts of THC that are so high that the products don’t even qualify as CBD (i.e., hemp) legally.

According to, 1 in 5 CBD products is contaminated with THC, so that’s worth considering if you use CBD products regularly. Adding to that, some CBD products deliberately contain up to 5% THC, depending on what’s legally permitted at the state level. So, read those labels!

Other Things That Can Cause a False Positive

Baby Soaps

A 2012 study in the Journal of Clinical Biochemistry called attention to the trend of baby wash products interfering with THC immunoassay tests, causing babies to have false positives. Some health professionals speculate that the THC imposter substance – although yet to be identified – has a chemical structure similar to that of THC. The substance is expected to be in one or more of the solvents in the soap.

Drug testing for babies can be done in cases of child abuse investigations or the presence of THC-associated congenital anomalies at birth. The products examined in the aforementioned study included:

  • Aveeno Soothing Relief Creamy Wash
  • CVS Night-Time Baby Bath
  • Johnson & Johnson’s Bedtime Bath
  • Johnson & Johnson’s Head-to-Toe Baby Wash

The study was careful to acknowledge that babies aren’t being intoxicated by these soaps; nor are there any effects associated with marijuana. But if your baby tests positive for THC, don’t be surprised if Child Protective Services pays you a visit unannounced.

Mouthwashes and Hand Sanitizers

Ethanol, a form of simple-grain alcohol, is a common ingredient in mouthwashes and hand sanitizers. Since drug tests can detect even trace amounts of alcohol long after your exposure to them, you can test positive if you’ve used these harmless products recently or regularly.

Secondhand Marijuana Smoking

Testing positive for THC after being around people smoking marijuana (often referred to as passive weed smoking) is possible but not probable – depending on your social circle. A study in the Journal of Analytical Toxicology concluded that to test positive from nonsmoker exposure to secondhand cannabis smoke, you would need to be around six smokers in a sealed room with no ventilation for at least one hour. Moreover, your test would need to be done within a few hours of your exposure.

The federal cutoff rate for THC in urine is 50 ng/mL, an amount nearly impossible to accrue under the above conditions. That said, if you’re a regular THC consumer, you wouldn’t be starting out from 0 ng/mL and can’t expect the same assurance. However, if you test positive from passive weed smoking but don’t smoke weed, just ask for confirmatory testing using a sample of your hair. That will go back in time much further than your secondhand session.

Photo by Pavel Danilyuk/ (Photo for illustrative purposes only)

Photo by Pavel Danilyuk/ (Photo for illustrative purposes only)

Last-Minute Tips for Drug-Free People Being Tested

If you weren’t able to avoid the foods, beverages, medicines, products or circumstances described above in time to have a factual drug test, be sure to disclose everything that might influence your test results. Tell the tester if you just took five Advil for debilitating menstrual cramps, had a medium pizza for breakfast (hey, it happens), or worked until the early morning and pumped yourself full of industrial-strength coffee all night. Other things to mention are recently or regularly taken:

  • Prescription drugs
  • Over-the-counter drugs
  • Vitamins
  • Dietary supplements
  • Herbal products

After you’ve disclosed everything, confirm that confirmatory testing (the aforementioned GC-MS and HPLC tests) will be done for any positive results you have.

If you expect imposter substances to sabotage you and you have a week or two before your drug test, consume detox foods daily. The five identified by Herbal Solutions are:

  • Almonds (unsalted, raw, organic only)
  • Turmeric (several tablespoons daily)
  • Asparagus (4 ounces daily)
  • Wild (not farm-raised) salmon
  • Apples (particularly Granny Smith)

In addition, Herbal Solutions advises that you consume lots of sugar-free fluids, exercise daily and avoid fatty, processed foods. The company also lists the following as part of an overall detox nutrition plan:

  • Water and water-rich foods (e.g., cucumbers, celery)
  • Fiber-rich foods (e.g., whole grains, legumes)
  • Cruciferous vegetables (e.g., broccoli, cauliflower, Brussels sprouts)
  • Leafy greens (e.g., spinach, kale)
  • Citrus fruits (e.g., lemons, oranges, grapefruits)
  • Berries (e.g., blueberries, strawberries, raspberries)
  • Garlic
  • Green tea
  • Ginger
  • Nuts
  • Seeds (exceptions: hemp and poppy)

There are also detox kits, which typically include dandelion leaves and three kinds of roots: rhubarb, burdock and goldenseal. These are often supplemented with detox drinks that promote liver function, hydration and increased urine production. The most effective ones contain natural ingredients, such as water, vitamins and minerals, electrolytes, and natural diuretics or herbal supplements.

Photo by Ba Tik /

Photo by Ba Tik /

If you know what specifically you will be tested for, review the guidance concerning timed food and medicine restrictions in “24-hour Urine and Food/Drug Restrictions” by Licking Memorial Health Systems. Additionally, you can consult the University of Illinois Chicago Drug Information Group article “What drugs are likely to interfere with urine drug screenings?” for lists of drug-testing cutoff values and lengths of time drugs can be detected in urine.

Good luck!

If you’re honestly drug-free (or, in the case of cannabis – which isn’t a drug – THC-free), you needn’t have a panic attack over a false-positive drug test. As this article shows, there are innumerable things that can trigger those, and drug-testing laboratories are well aware of that and have backups in place. Just be honest up front with the tester and try the above ideas, with your physician’s guidance and approval.

Kathleen Hearons is a writer, editor, linguist and voice over actor from Los Angeles. She specializes in creative writing and research-intensive analysis and reporting.  




Sources and Suggested Reading

7 U.S.C. 38, Subchapter VII: Hemp Production (Title 7 – Agriculture, Chapter 38 – Distribution and Marketing of Agricultural Products). U.S. Congress. Accessed December 11, 2023.

“8 Tips to Prepare for a Drug & Alcohol Test.” ARCpoint Labs. August 15, 2022. Accessed December 10, 2023.

“12 Common Household Products and Foods that can Cause False Positive Drug Tests.” Oro Recovery. August 14, 2020. Accessed December 10, 2023.

“24-hour Urine and Food/Drug Restrictions.” Licking Memorial Health Systems. December 20, 2021. Accessed December 10, 2023.

Baird, Christopher S. “Do poppy seeds contain narcotics?.” West Texas A&M University. November 12, 2014. Accessed December 11, 2023.

“Best THC Detox Options of 2023 – Trustworthy Product Kits from Top Brands.” HeraldNet. December 2, 2023. Accessed December 11, 2023.

“Can a Drug Test Lead to a False Positive?.” Last updated November 8, 2023. Accessed December 10, 2023.

“Can food and drinks Give False Positive drug test?.” Australia Drug Testing. Accessed December 10, 2023.

“Can You Eat Before A Drug Screening?.” ReliaLab Test. Accessed December 10, 2023.

“CBD & Drug Testing: Your Questions Answered.” DNA Legal. August 18, 2020. Accessed on December 11, 2023.

Cone, Edward J., et al. “Non-Smoker Exposure to Secondhand Cannabis Smoke. I. Urine Screening and Confirmation Results.” Journal of Analytical Toxicology, Vol. 39, Iss. 1 (January 2015): 1-12. doi: 10.1093/jat/bku116. Accessed December 11, 2023.,circumstances%20where%20exposure%20is%20obvious.

Cotten, Steven W., et al. “Unexpected interference of baby wash products with a cannabinoid (THC) immunoassay.” Journal of Clinical Biochemistry, Vol. 45, Iss. 9 (June 2012): 605-609. doi: 10.1016/j.clinbiochem.2012.02.029. Accessed December 11, 2023.

“Dietary Restrictions for Urine Tests.” MyMichigan Health, University of Michigan. Accessed December 10, 2023.

DOT Rule 49 CFR Part 40 Section 40.85, Subpart F – Drug Testing Laboratories. U.S. Department of Transportation. Accessed December 11, 2023.

DOT Rule 49 CFR Part 40 Section 40.139, Subpart G – Medical Review Officers and the Verification Process. U.S. Department of Transportation. Accessed December 11, 2023.

“Drug Testing.” MedlinePlus, National Library of Medicine, National Institutes of Health, U.S. Department of Health and Human Services. Last updated June 7, 2022. Accessed December 10, 2023.

“Drug Testing FAQs.” Last updated April 17, 2022. Accessed December 10, 2023.

Frost, Alex. “6 Best Natural THC Detox Drinks for Medical Cannabis Patients.” Lyphe Clinic. September 21, 2023. Accessed December 10, 2023.

Garamone, Jim. “Service Members Should Avoid Foods With Poppy Seeds.” U.S. Department of Defense. February 22, 2023. Accessed December 10, 2023.

Gerberich, Amanda. “What drugs are likely to interfere with urine drug screens?.” Drug Information Group, College of Pharmacy, University of Illinois Chicago. May 2021. Accessed December 10, 2023.

Hearons, Kathleen. “The Illogic of Illegal Weed: A Comprehensive Analysis.” Head Magazine. Accessed December 27, 2023.

“Heavy Metals in Seafood.” Singapore Food Agency, Government of Singapore. Accessed December 11, 2023.

“How to avoid a false positive drug test and the factors that can cause it.” DNA Legal. December 15, 2020. Accessed December 10, 2023.

“How to Get Weed Out of Your System: Ways to Cleanse Your Body.” Zinnia Health. July 10, 2023. Accessed December 11, 2023.

“How To Use Detox Pills For Drug Test Success: Best THC Detox Pills Revealed.” Only My Health. Last updated November 24, 2023. Accessed December 11, 2023.

“Marijuana Detox: Clearing the Haze Around Detoxing from Marijuana.” The Edge Treatment Center. Accessed December 11, 2023.

Martins, Kris. “What Can Cause a False Positive Drug Test.” August 22, 2023. Accessed December 10, 2023.

“Memorandum for Secretaries of the Military Departments: Warning Regarding Poppy Seed Consumption and Military Drug Testing,” Redacted. Under Secretary of Defense, U.S. Department of Defense. February 17, 2023. Accessed December 11, 2023.

Olsson, Regan. “What Medications Can Cause False Positives on Drug Tests?.” Banner Health. January 7, 2023. Accessed December 10, 2023.

Powell, Amie. “Can You Eat Before a Drug Test?.” USA Mobile Drug Testing. Last updated December 11, 2023. Accessed December 11, 2023.

Powers, Deborah, Stephen Erickson and Madeleine J. Swortwood. “Quantification of Morphine, Codeine, and Thebaine in Home-Brewed Poppy Seed Tea by LC-MS/MS.” Journal of Forensic Sciences, Vol. 63, Iss. 4 (July 2018): 1229-1235. Accessed December 11, 2023.

Reisfield, Gary. “Can eating poppy seeds affect drug test results? An addiction and pain medicine specialist explains.” The Conversation. February 28, 2023. Accessed December 10, 2023.

“Review the Top-Ranked Best THC Detox Methods on the Market.” Bellevue Reporter. November 20, 2023. Accessed December 11, 2023.

Santos-Longhurst, Adrienne. “Can Eating Poppy Seeds Give You a Positive Drug Test?.” Healthline. May 23, 2019. Accessed December 10, 2023.

Schaefer, Anna. “Marijuana Detox: What You Should Know.” Healthline. Last updated January 26, 2019. Accessed December 11, 2023.

Shea, Kristen. “5 Detox Foods To Eat Before A Drug Test.” Magic Detox™, Herbal Solutions, LLC. Last updated February 10, 2023. Accessed December 10, 2023.

Taylor, Vivien, et al. “Human Exposure to Organic Arsenic Species from Seafood.” The Science of the Total Environment, Vol. 580 (2017): 266-282. doi:10.1016/j.scitotenv.2016.12.113. Accessed December 11, 2023.

“The Best Defense for False Positive Drug Test.” Overland. Last updated May 11, 2023. Accessed December 10, 2023.

“Top-Rated Best THC Detox Methods and Product Kits That Actually Work.” Kirkland Reporter. December 1, 2023. Accessed December 10, 2023.

“Unwashed Poppy Seed.” Drug & Chemical Evaluation Section, Diversion Control Division, Drug Enforcement Administration, U.S. Department of Justice. November 2019. Accessed December 11, 2023.

Wagener, Dan. “How Long Does Marijuana (Weed) Stay in Your System?.” American Addiction Centers. Last updated September 13, 2022. Accessed December 11, 2023.

“What Can Cause False Positives for Drug Tests?.” Silver Pines Treatment Center. Accessed December 10, 2023.

“What foods can throw off a drug test?.” Sivertson & Barrette Law. October 2021. Accessed December 2023.