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This article was co-authored by wikiHow staff writer, Bailey Cho. Bailey Cho is an Editing Fellow at wikiHow, based in Dallas, TX. She has over 2 years of editorial experience, with work published in student journals and lifestyle publications. Bailey graduated from the University of Texas at Austin with a B.A. in Advertising and a Minor in Business.
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Many employers administer oral swab tests to check for drug use among their employees. Mouth swab tests are much easier to pass than a urine or blood test, since they usually can't detect drug use for more than a couple of days. However, the technology is recent and always changing, so it’s best to take precautions. Most online advice is ineffective or even harmful, but there are a few steps you can take to increase your odds. In reality, though, the only effective way to make sure you’ll pass a swab test is to abstain from drugs for at least 48 hours beforehand.
Steps
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Suck citric acid candies to make your saliva more acidic. Research shows that citric acid candy can stimulate oral fluid (saliva) production and change the pH and concentration of drugs in your saliva.[1] If you only have 5-10 minutes before a mandatory mouth swab test, consider popping 2 or 3 sour candies in your mouth. Suck them (rather than chewing) to get as much citric acid out of the candies as possible.- In fact, one study shows that acidic stimulation lowers concentrations of codeine by about 50%.[2]
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Chew a couple of pieces of gum to increase your saliva production. Chewing on a piece of gum stimulates saliva production, which may dilute the concentration of drugs in your saliva. According to research, chewing gum can also change the pH and concentration of drugs in your saliva, potentially making the mouth swab test less effective.[3] If you have a choice between different flavors, opt for a cinnamon or strong citrus gum.- It wouldn’t be a bad idea to carry a pack of gum with you to work every day if you’re concerned about surprise swab tests.
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Rinse your mouth with hydrogen peroxide 5 minutes before the test. Some believe that swishing with hydrogen peroxide can clean their saliva and beat a mouth swab test.[4] There is no scientific guarantee of success, but hydrogen peroxide may interfere with the test and decrease the chances of a positive reading. Rinse your mouth with hydrogen peroxide for 30 seconds right before your test, then spit it out into the sink. Be careful not to swallow any peroxide, since it can cause mild to severe gastrointestinal effects.[5]- Avoid using alcohol-based mouthwashes, as they can lead to a false positive result on a drug test.[6]
Tip: If you don’t have hydrogen peroxide, try rinsing with a mouthwash.
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Avoid taking any drugs for 48 hours before the test. Most mouth swab tests can only detect drugs ingested 5-48 hours beforehand.[7] Most oral swab tests are administered to check for marijuana use, as the THC compounds in marijuana are easily detectable in saliva. To be on the safe side, lay off whatever other drugs you may be using for 48 hours. Spending at least 48 hours drug-free is recommended to be on the safe side, especially if you are a heavy user. -
Sip water throughout the day to increase saliva production. Some believe that drinking a lot of water can help dilute drug metabolites in the saliva.[10] While there isn’t scientific evidence that supports this method, being hydrated is important for a successful saliva test. Stay hydrated by sipping 8 ounces of water every hour leading up to your test time, and avoid coffee, tea, soda, or Gatorade one hour before your test.[11]- Chemicals get into your saliva from your bloodstream, which can't be “flushed out” the same way. Still, there’s no harm in upping your hydration and saliva output for 48–72 hours before the test.
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Brush your teeth twice daily to remove lingering saliva. This isn’t a very effective or scientifically-backed method, but it might slightly decrease the amount of THC (or chemicals from other drugs) lingering in your mouth.[12] Use a new toothbrush and a reputable brand of toothpaste, and scrub your teeth for at least 2 minutes after breakfast and dinner. Make sure to scrub your tongue and cheeks, too. Rinse and spit at the end.- Brushing your teeth thoroughly and consistently won’t work any miracles, but it can help remove particles stuck between your teeth and along the gumline.
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Gargle every 15 minutes for 4–5 hours before the test. This isn’t a reliable way to pass a mouth swab test, but some believe it can help. Step into the bathroom, take a big swig of mouthwash, and gargle it for 20–30 seconds. Repeat this every quarter hour before your swab test. Rinsing with mouthwash may temporarily dilute the concentration of THC (or other drug chemicals) in your saliva, which can make the drugs slightly harder to detect.[13]- Gargling may remove some drug residue from your mouth, but it doesn’t clear the drug from your saliva glands and tissues.[14]
Expert Q&A
Video
Tips
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Eating poppy seeds can make you test positive for heroin, but usually only for about an hour.[15] Most drug testers now follow updated guidelines that avoid longer periods of false positives from poppy seeds. However, this also makes them less likely to accept the “poppy seed defense.”Thanks
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Dehydration or dry mouth can reduce saliva volume, potentially decreasing the sensitivity of the mouth swab test.[16]Thanks
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Being in the same room as marijuana smoke is unlikely to affect your saliva for longer than 30–45 minutes.[17]Thanks
Warnings
- If a test administrator notices you are trying to “cheat” or tamper with your mouth swab test, they can report a refusal to test.[19] This is often equivalent to an automatic failure.Thanks
- Drinking or rinsing your mouth with cleaning products can seriously injure or kill you. Do not trust any advice that tells you to do so!Thanks
References
- ↑ https://pmc.ncbi.nlm.nih.gov/articles/PMC1579288/
- ↑ https://www.sciencedirect.com/science/article/abs/pii/S0379073805001234?via=ihub
- ↑ https://pmc.ncbi.nlm.nih.gov/articles/PMC1579288/
- ↑ https://yourhealthmagazine.net/article/addiction/find-out-how-far-back-mouth-swab-drug-tests-can-detect-usage/
- ↑ https://wwwn.cdc.gov/TSP/ToxFAQs/ToxFAQsDetails.aspx?faqid=305&toxid=55
- ↑ https://www.rapidtestinglab.com/health-resources/can-mouthwash-with-alcohol-make-me-fail-my-drug-test/
- ↑ https://pubmed.ncbi.nlm.nih.gov/15228165/
- ↑ https://pubmed.ncbi.nlm.nih.gov/24819969/
- ↑ https://www.attosure.co.uk/blog/2025/6/will-codeine-show-up-on-a-drug-test/
- ↑ https://www.nursingscience.org/pass-a-saliva-swab-drug-test
- ↑ https://machias.edu/return/2021/08/02/what-steps-should-i-take-to-help-ensure-my-shield-t3-saliva-pcr-test-is-successful/
- ↑ https://www.nursingscience.org/pass-a-saliva-swab-drug-test
- ↑ https://www.sciencedirect.com/science/article/pii/S1882761621000065
- ↑ https://surehire.com/blog/2021/04/23/pot-topics-3-common-oral-fluid-adulteration-methods/
- ↑ https://pmc.ncbi.nlm.nih.gov/articles/PMC2700061/
- ↑ https://exactbackgroundchecks.com/factors-affecting-mouth-swab-drug-test-duration/
- ↑ https://pubmed.ncbi.nlm.nih.gov/16419389/
- ↑ https://my.clevelandclinic.org/health/diagnostics/oral-drug-test
- ↑ https://wfqa.com/specimen-validity-testing/
About This Article
Medical Disclaimer
The content of this article is not intended to be a substitute for professional medical advice, examination, diagnosis, or treatment. You should always contact your doctor or other qualified healthcare professional before starting, changing, or stopping any kind of health treatment.
If you have to pass a mouth swab drug test and you don’t have time to detox first, there are a few things you can do to improve your chances of passing. Try sucking on 2 or 3 sour candies 5 to 10 minutes before you have to take the test, since high levels of sugar and acid in your saliva can make drugs harder to detect. Chewing on citrus or cinnamon gum can help for the same reasons, plus it will stimulate your mouth to produce more saliva, which may dilute any traces of drugs. You can also make it harder for the test to detect drugs by swishing some hydrogen peroxide in your mouth for 30 seconds, then spitting it out. Don’t use an alcohol-based mouthwash, though, since this could create a false positive result for alcohol abuse. For tips on how to prepare for a mouth swab test in advance, read on!
Reader Success Stories
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"I have taken several mouth tests and smoke daily. The first test I put water in my mouth and soaked up as much as I could into test. I passed a surprise test also. I took another and passed with same thing a lot of water in mouth. "..." more
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