How to Pass a Mouth Swab Test

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Last Updated: November 12, 2024 Fact Checked

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 from more than a couple days ago. 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 small ways to increase your odds. In reality, though, the only truly effective way to make sure you'll pass a swab test is to abstain from drugs for at least 2–3 days before the swab test.

Method 1

Method 1 of 2:

Passing the Test with No Prep Time

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The more acidic and sugary your saliva becomes, the more difficult it is for drugs to be detected in it. So, if you only have 5–10 minutes before you'll be given a mandatory drug swab test, pop in 2 or 3 sour citrus candies. Suck them (rather than chewing) to get as much of the acidic citrus flavoring out of the candies as you can!^{[1]
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Note: Multiple studies have shown that swab tests for drug use yield lower results right after people sucked citrus candies.
2
Chew a couple of pieces of gum to increase your saliva production. Chewing on a piece of gum stimulates your saliva production, which will dilute the concentration of any drugs in your saliva. Chewing gum will also change the chemical makeup of your oral fluids, which can make the mouth swab test less effective.^{[2]
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Go to source} If you have a choice between different flavors, opt for a cinnamon or strong citrus flavors.
- It wouldn't be a bad idea to carry a pack of gum with you to work on a daily basis if you're concerned about surprise swab tests.
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3
Rinse your mouth with hydrogen peroxide 5 minutes before the test. Peroxide is what's known as an “adulterant”: a chemical that interferes with the swab test's ability to accurately detect drugs in your saliva. Take a gulp of peroxide just before your test, and swish it around inside your mouth for 30 seconds. Then spit it out into the sink.^{[3]
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Go to source} Be careful not to accidentally swallow any of the peroxide. It's can cause internal harm if ingested.
- Avoid using alcohol-based mouthwashes, though, as they can lead to a false positive result for alcohol abuse.
Tip: If you don't have peroxide, try rinsing with a mouthwash, which is also an adulterant.

Method 2

Method 2 of 2:

Preparing in Advance

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1
Avoid taking any drugs for 72 hours before the test. The mouth swab test can only reliably detect drugs ingested in the last 48–72 hours.^{[4]
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Go to source} 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, though, also lay off of whatever other drugs you may be using for 72 hours. Spending at least 72 hours drug-free is recommended to be on the safe side, especially if you are a heavy user.
- Also avoid taking cough suppressant medication that contains codeine.
The THC molecules in your bloodstream (and saliva) bind easily to fat. Then, when the fat is eliminated from your body, it takes the THC with it, making your drug use much more difficult to detect. So, for 2 days before the oral swab test, eat high-fat foods as part of every meal to flush the THC out of your body.^{[5]
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Tip: Items from fast food restaurants and highly processed foods are high in fat. For a healthier option, though, try eating tuna or salmon, along with avocados, whole eggs, nuts, and cheese.
3
Sip water throughout the day to keep up saliva production. In theory, new saliva will have lower concentrations of drug-related chemicals than older saliva. Stay hydrated by sipping water, herbal tea, or fruit juice frequently, so you can produce more saliva. Also avoid liquids that dehydrate your body, including coffee, black tea, and alcohol.^{[6]
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- 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.
4
Brush your teeth twice daily to remove lingering old saliva. This isn't a very effective method, but it might slightly decrease the amount of THC (or chemicals from other drugs) lingering in your mouth. 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 as well as your teeth. Rinse and spit at the end.^{[7]
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- Brushing your teeth thoroughly and consistently won't work any miracles, but it will ensure that old oral fluids aren't built up in your mouth.
5
Gargle every 15 minutes for 4–5 hours before the test. If you get to work and find out that you have a swab test in 4 or 5 hours, don't panic! Step into the bathroom, take a big mouthful of water, and gargle with it for 20–30 seconds. Repeat this every quarter hour before your swab test. Rinsing with water will dilute the concentration of THC (or other drug chemicals) in your saliva and will make the drugs slightly harder to detect.^{[8]
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- The effect this will have will be small and short-lived.^{[9]
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  Go to source} But it's also one of the easiest steps you can take.

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Eating poppy seeds can make you test positive for heroin, but usually only for about an hour.^{[10]
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Go to source} 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.”

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Being in the same room as marijuana smoke is unlikely to affect your saliva for longer than 30–45 minutes.^{[11]
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The mouth swab test won't return any result at all if it doesn't get enough saliva. Showing up with a dry mouth will just make the test longer and more unpleasant.

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Warnings

Drinking or rinsing your mouth with cleaning products will seriously injure or kill you. Do not trust any advice that tells you to do so!

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