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Terms of Use wikiHow is where trusted research and expert knowledge come together. Learn why people trust wikiHow
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Health
Medicines and Drugs
Recreational Drugs
Drug Testing
Effective Ways to Dispute a False Positive Drug Test Download Article Written by Jennifer Mueller, JD
Last Updated: May 1, 2025 References
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Getting Retested
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Preventing a False Positive
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Tips
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Warnings
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This article was written by Jennifer Mueller, JD. Jennifer Mueller is an in-house legal expert at wikiHow. Jennifer reviews, fact-checks, and evaluates wikiHow's legal content to ensure thoroughness and accuracy. She received her JD from Indiana University Maurer School of Law in 2006. There are 8 references cited in this article, which can be found at the bottom of the page. This article has been viewed 41,150 times.
Drug tests are a prerequisite for employment at many private and government employers, as well as if you want to participate in many sports. If you've never had anything to do with illegal drugs, you're probably thinking it's no big deal — until you get caught off-guard by a false positive. It's not a stretch for drug tests to be wrong, and there are many common substances that can trigger a false-positive result. If you're certain that the result is false, immediately demand a re-test. Typically, your original sample will be retested using a more advanced testing method that separates out substances that might interfere with the results.[1]XResearch source
Steps
Method 1 Method 1 of 2:
Getting Retested
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1 Ask for a re-test as soon as possible. Having a test come back positive when you know the result is inaccurate can be a stressful situation. Take a few deep breaths to calm yourself, then let the administrator who ordered the test know immediately. Say you believe the result was a false positive and you'd like to be re-tested.
For example, if you got a drug test to participate on your school's soccer team and it came back positive, you might approach your coach and explain you believe it was a false positive because you haven't taken any of the drugs tested. Then, ask for a second test to confirm your suspicions.
If your boss or coach seems reluctant to allow a re-test, try telling them that you're willing to pay for it yourself.
2 Disclose substances you've taken that might have caused the result. If you were taking something that might've caused a false-positive result, the lab can do other tests to verify that you haven't touched the drugs being tested. Letting your boss or coach know about these substances can go a long way towards convincing them you deserve a second chance. Everyday substances that might cause a false positive include:[2]XResearch source
Over-the-counter cold medicines, such as Dimetapp (false positive for amphetamines and methamphetamines)
Sleep medications, such as Unisom or Zzzquil (false positive for opiates)
Allergy medications, such as Benadryl or Allegra-D (false positive for opiates or amphetamines)
Ibuprofen and other NSAIDs (false positive for marijuana, barbiturates, benzodiazepines)
Antidepressants, such as Zoloft (false positive for benzodiazepines)
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3 Request a more advanced testing method to confirm your suspicions. Ask for a testing method that separately analyzes the different substances that can cause a false positive on the first go-around. The gas chromatography-mass spectrometry (GC-MS) test and the high-performance liquid chromatography (HPLC) test are standard secondary tests used by most labs.[3]XResearch source
GC-MS is the most accurate and sensitive testing method. However, it's also expensive, time-consuming, and requires technicians with a high level of expertise.[4]XResearch source While costs vary, if you have to pay for the test yourself, expect to pay over $300.[5]XResearch source
4 Get help from your union or a private attorney. Even if you fail in your efforts to get a retest, all is not lost. If you're a member of a union, consult a union leader — they'll file a grievance on your behalf. If you're not a member of a union, you still might be able to find a private attorney to assist you.[6]XResearch source
Time is of the essence, so talk to someone as soon as possible — especially if you risk losing your job (or a job offer) because of a false-positive test result. Filing a grievance or legal challenge can help delay any actions that might be taken against you because of the test result.
If hiring an attorney isn't in your budget, talk to them about payment plans and other options, such as sliding-fee payment scales based on income.
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Preventing a False Positive
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1 Avoid eating poppy seeds on the day of your test. It may sound like an urban legend, but it's absolutely true that you can test positive for opiates after eating poppy seeds. The US government has raised the threshold for opiate detection to avoid this particular false-positive, but it's still a possibility. To prevent this false positive entirely, don't eat anything with poppy seeds on or in it if you know you're going to be taking a drug test within the next 12 to 24 hours.[7]XResearch source
If you're hit with a surprise test, let the lab technicians know that you ate something with poppy seeds. They'll tell you if a false positive is possible.
While thresholds have been raised in the US, the threshold for opiate detection is still low enough in some countries, such as Australia and New Zealand, for you to get a false-positive result after eating poppy seeds.
2 Stay away from other people smoking marijuana. While research confirms it's unlikely that you'll test positive for THC simply from being around other people who are smoking, it's still a good idea to avoid passive inhalation of marijuana smoke if you're not partaking yourself. You especially want to avoid this scenario in the 24 hours before your drug test.[8]XResearch source
While it's an evolving issue, as of 2020, most employers can still test for marijuana usage. Even if recreational use is legal in your state, the substance is still illegal at the federal level.[9]XResearch source
3 Get a statement from your doctor for prescribed medications. Drug tests are designed to detect illegal drug use — but if you have a prescription, your use isn't illegal. Even if your employer doesn't require you to report prescribed medications, it's still good practice to do so if you want to avoid a false-positive.[10]XResearch source
If you test positive for a drug that you have a prescription for, the lab technicians will use this information to determine how much of that drug you should have in your system, given your prescription. If you have more than that amount, you might have problems.
Some other prescriptions, including many common anti-depressants, can cause false positives. If you're taking an anti-depressant, ask your doctor if it could potentially interfere with a drug test. If it could, report it before the drug test.[11]XResearch source
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Tips
Go over the organization's anti-drug policy and the substances you'll be tested for before you agree to take the drug test. If there's anything you're unsure about, ask someone in management or human resources to explain it to you.[12]XResearch sourceThanks Helpful 0 Not Helpful 0
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Warnings
This article primarily discusses disputing a false positive drug test in the US. If you're taking a drug test in another country or for an international organization, there may be different rules. Talk to an administrator or consult the drug test policy of the organization. Thanks Helpful 0 Not Helpful 0
If you get re-tested, you may have to pay for the second drug test out of your own pocket. Thanks Helpful 0 Not Helpful 0
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Written by: Jennifer Mueller, JD Doctor of Law, Indiana University This article was written by Jennifer Mueller, JD. Jennifer Mueller is an in-house legal expert at wikiHow. Jennifer reviews, fact-checks, and evaluates wikiHow's legal content to ensure thoroughness and accuracy. She received her JD from Indiana University Maurer School of Law in 2006. This article has been viewed 41,150 times. 18 votes - 90% Co-authors: 4Updated: May 1, 2025 Views: 41,150 Categories: Drug Testing In other languagesSpanish
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Yes No Advertisement Cookies make wikiHow better. By continuing to use our site, you agree to our cookie policy. Written by: Jennifer Mueller, JD Doctor of Law, Indiana University Co-authors: 4Updated: May 1, 2025 Views: 41,15090% of readers found this article helpful. 18 votes - 90% Click a star to add your vote
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Written by: Jennifer Mueller, JD Doctor of Law, Indiana University This article was written by Jennifer Mueller, JD. Jennifer Mueller is an in-house legal expert at wikiHow. Jennifer reviews, fact-checks, and evaluates wikiHow's legal content to ensure thoroughness and accuracy. She received her JD from Indiana University Maurer School of Law in 2006. This article has been viewed 41,150 times. 18 votes - 90% Co-authors: 4 Updated: May 1, 2025 Views: 41,150 Categories: Drug Testing In other languagesSpanish 
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1 Ask for a re-test as soon as possible. Having a test come back positive when you know the result is inaccurate can be a stressful situation. Take a few deep breaths to calm yourself, then let the administrator who ordered the test know immediately. Say you believe the result was a false positive and you'd like to be re-tested. 
2 Disclose substances you've taken that might have caused the result. If you were taking something that might've caused a false-positive result, the lab can do other tests to verify that you haven't touched the drugs being tested. Letting your boss or coach know about these substances can go a long way towards convincing them you deserve a second chance. Everyday substances that might cause a false positive include:[2] 
3 Request a more advanced testing method to confirm your suspicions. Ask for a testing method that separately analyzes the different substances that can cause a false positive on the first go-around. The gas chromatography-mass spectrometry (GC-MS) test and the high-performance liquid chromatography (HPLC) test are standard secondary tests used by most labs.[3] 
4 Get help from your union or a private attorney. Even if you fail in your efforts to get a retest, all is not lost. If you're a member of a union, consult a union leader — they'll file a grievance on your behalf. If you're not a member of a union, you still might be able to find a private attorney to assist you.[6] 
1 Avoid eating poppy seeds on the day of your test. It may sound like an urban legend, but it's absolutely true that you can test positive for opiates after eating poppy seeds. The US government has raised the threshold for opiate detection to avoid this particular false-positive, but it's still a possibility. To prevent this false positive entirely, don't eat anything with poppy seeds on or in it if you know you're going to be taking a drug test within the next 12 to 24 hours.[7] 
2 Stay away from other people smoking marijuana. While research confirms it's unlikely that you'll test positive for THC simply from being around other people who are smoking, it's still a good idea to avoid passive inhalation of marijuana smoke if you're not partaking yourself. You especially want to avoid this scenario in the 24 hours before your drug test.[8] 
3 Get a statement from your doctor for prescribed medications. Drug tests are designed to detect illegal drug use — but if you have a prescription, your use isn't illegal. Even if your employer doesn't require you to report prescribed medications, it's still good practice to do so if you want to avoid a false-positive.[10] 
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