How Does a Mouth Swab Drug Test Work?

Young male doctor in protective suit taking swab test from young female patient

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A mouth swab drug test is a screening tool used to detect the presence of certain substances in your system using your saliva.

This type of test is quickly becoming one of the most popular screening tools for drugs because of the ease with which it can be done. It offers almost instant results and is generally low-cost. It is also less invasive than some common tests used to detect substances, such as a urine or blood test.

A mouth swab drug test is most useful when detecting if a person very recently abused a drug or substance.

This article describes what you can expect during a mouth swab drug test and why you might need to take it. It also covers which drugs they can test for, how soon a drug can be detected in your saliva after taking them, why you might need to take a mouth swab drug test, and how accurate a mouth swab drug test is.

What to Expect During the Test 

A mouth swab test is done by swiping the inside of your cheek or underneath your tongue with what looks like a long Q-tip, with a sponge-like material at the end. This can either be done for you or you might be asked to swipe the tool yourself.

A saliva sample is taken using this tool and tested for whatever substance you are being required to test for. You don’t need to do anything to prepare for a mouth swab drug test, and the whole process is concluded in a manner of minutes. 

You are typically advised not to eat or drink anything for about 10 minutes before the test is conducted.

If the person conducting the test came to your home or place of work, they’d need to take the samples back to their lab to analyze your saliva. But, depending on the kit used, some results can be produced on-site.

Certain kits provide a nearly instant result once the sample has been put on them, and some tests produce results within 24 hours.

Why You Might Need a Mouth Swab Test 

A mouth swab drug test might be conducted for several reasons. It’s particularly common in workplaces that have a strict policy against drug abuse.

A test might be ordered as part of a routine checkup in the company or if you’ve been suspected of abusing drugs.

Mouth swab drug tests are also ideal for places where frequent drug tests need to be conducted, such as rehabilitation facilities.

In addition, certain industries that deal with transportation, national safety, or public safety are legally required to test their employees for drug use.

If you or a loved one are struggling with substance use or addiction, contact the Substance Abuse and Mental Health Services Administration (SAMHSA) National Helpline at 1-800-662-4357 for information on support and treatment facilities in your area.

For more mental health resources, see our National Helpline Database.

Which Drugs Can Be Detected? 

A mouth swab drug test can be used to detect several substances and drugs. Some of the most common drugs tested for using this method include: 

How Soon Can These Drugs Be Detected?  

How soon a drug can be detected and how long it remains present in your saliva depends on the drug being tested for.

Here are some of the most common substances checked for during a mouth swab drug test and how soon they can be detected in your saliva:

  • Benzodiazepines: Also known as "benzos," some drugs that fall under this category can be detected for up to 10 days after they’ve been used. However, a benzodiazepine such as Ativan gets metabolized more quickly by the body and may only be detectable for around five days. 
  • Marijuana: A mouth swab test can detect THC in your system as soon as 24 hours after consumption.
  • Opiates: Most opiates such as heroin are detectable through saliva for about 24 to 36 hours after they’ve been consumed.
  • MDMA: More commonly known as ecstasy or molly, MDMAs can be detected through your saliva as soon as an hour after they’ve been consumed. However, these substances pass through the body’s systems quickly and become almost undetectable 24 hours after consumption.
  • Methamphetamine: Methamphetamine can be detected using a mouth swab drug test as soon as ten minutes after it has been used. It can remain detectable for up to four days later, especially with frequent users of the drug.

Although convenient, mouth swab drug tests do suffer from one serious disadvantage. They have a shorter testing time range than other methods of drug testing. This means that several drugs become undetectable in the saliva just a few days after they’ve been used.

A person looking to take advantage of this only has to wait a few days to circumvent the test and come out clean, depending on the substance used. Some test administers use more than one kind of screening tool to avoid this issue.

There’s no exact science as to how long drugs can be detected in your saliva. Research shows that several factors could affect the detection time of a drug in any individual.

These factors include:

  • The quantity of the substance taken
  • The route of administration
  • The frequency in which the person being tested uses drugs

How Effective Is a Mouth Swab Drug Test? 

These tests are most effective for detecting very recent cases of drug abuse. If a person takes a test just a couple of days after using a drug, a saliva test might not detect it. However, when done promptly and properly these tests are very effective in detecting drug abuse.

Additionally, the results of a mouth swab test will not be affected by using mouthwash, eating some food, or drinking a lot of water. And, because the samples are collected in plain view they can’t be swapped out with anyone else’s.

Some research does show that citric acid sweets or chewing gum could change the concentration of certain drugs in your saliva. It was shown to reduce concentrations of cocaine, codeine, and methamphetamines to varying degrees.

3 Sources
Verywell Mind uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. Drummer OH. Drug testing in oral fluid. Clinical Biochemist Reviews. 2006;27(3):147-159.

  2. Substance Abuse and Mental Health Services Administration. Considerations for safety- and security-sensitive industries. June 24, 2020

  3. Arroyo A, Mora A, Sanchez M, Barbal M, Palahi M. Times of detection of drugs of abuse in saliva: study of arrested population. Journal of Forensic Research. 2011;02(01).

By Toketemu Ohwovoriole
Toketemu has been multimedia storyteller for the last four years. Her expertise focuses primarily on mental wellness and women’s health topics.