A mouth swab drug test screens for substances in your system, such as illicit drugs, prescription medications, alcohol, or marijuana. The test is performed using an oral swab that collects saliva.
Results of swab drug tests, also known as saliva drug tests or oral fluids drug tests, are often available within minutes. While used less often than urine testing, saliva screenings are common, and the results are considered highly accurate.
A variety of drugs and substances can be detected by a mouth swab test. However, it's important to understand the limitations of these tests and your legal rights when you're being tested.
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How Does a Mouth Swab Drug Test Work?
An oral fluid test is quick and easy. You may have the screening done at a lab or testing site, but this kind of test can also be done on the roadside by a police officer.
To ensure accurate results, follow these steps.
- Don't eat or drink for 10 minutes prior to the test.
- Before an oral swab, the tester will check your mouth to ensure there's no substance or device present that could interfere with collecting a clean sample.
- A sterilized swab is placed inside the mouth to collect saliva secreted from glands.
- The swab is removed and placed into a collection container.
- Depending on the type of test, the results may be analyzed immediately and results available in minutes, or the sample may need to be sent to a lab overnight for testing.
If you suffer from dry mouth or have difficulty generating enough saliva, the tester can give you water, which you can drink or use to rinse your mouth. You will then need to wait 10 minutes before the sample can be collected.
Why You Can't Eat or Drink
Certain foods or drinks can change the pH (acid-base) level of saliva and can alter the test results, potentially causing a false positive or false negative result. This includes vinegar, citrus, bicarbonate, fruit juices, and salt. Even chewing gum needs to be avoided to ensure that the results are not tainted.
Home testing kids are also available. You need to follow the instructions for these carefully. In some instances, you may need to complete the self-test under supervision.
When Are Mouth Swab Drug Tests Used?
Saliva drug tests are quick and easy ways to check for drug use or monitor health. They are commonly used for the following situations:
- Pre-employment qualification
- Periodic workplace evaluation
- Pain management monitoring
- Substance abuse treatment
- Impaired driver testing
Employers and healthcare facilities often use saliva tests because there are several benefits over other types of drug screenings, including urine tests, blood draws, and hair analyses. These advantages include:
- Relatively inexpensive
- Quick and convenient
- Can detect current usage
- Receive results in minutes
- Rapid tests are difficult to cheat because the tester is there with you the entire time
What Do Oral Fluid Screenings Test For?
Mouth swab drug tests can detect a variety of different substances. The following are among the things that might show up in a mouth swab screen:
- Alcohol
- Amphetamines (including crystal meth)
- Barbiturates
- Benzodiazepines
- Cocaine
- Gamma-hydroxybutyrate (GHB)
- Ketamine ("special K")
- Marijuana (THC)
- MDMA ("ecstasy")
- Methamphetamine
- Methadone
- Opiates (like morphine and heroin)
- Opioids (like hydrocodone, oxycodone, and fentanyl)
- Performance-enhancing drugs (like anabolic steroids)
- Phencyclidine (PCP)
- Rohypnol ("roofies")
How Accurate Is a Mouth Swab Drug Test?
If the mouth swab drug test is performed correctly, the test can be highly accurate, sporting a sensitivity of up to 100% and a specificity of 86% for certain drugs. (Sensitivity refers to the percentage of correct positive results, while specificity refers to the percentage of correct negative results.)
It is still possible for some tests to give inaccurate readings. For instance, false positive rates for oral fluid screenings for cannabis, cocaine, methamphetamine, and opioids are between 3% and 7%.
Also, some drugs are not well detected by the current generation of tests. The drugs for which saliva-based tests are least accurate are benzodiazepines and amphetamines,
Factors Influencing Results
In addition to eating and drinking before the test, there are other factors that can influence the accuracy of saliva testing, such as:
- Your age (which can impact how quickly or slowly a drug is metabolized)
- Your liver or kidney function (which can increase or decrease how fast a drug leaves the system)
- How much of a substance you consumed (large doses vs. smaller doses)
- How frequently a substance is used (as certain drugs can accumulate in the system)
- The quality of the substance (as some drugs are "cut" with inactive fillers)
How Long After Use Can a Drug Be Detected?
In many cases, a drug can be detected in saliva as early as one hour after a dose. Thereafter, substances can remain detectable from several hours to several days before gradually dropping to undetectable levels. In general, drugs stay in saliva anywhere from five to 48 hours.
The following are the average windows for when drugs are detectable in oral fluid.
| Drug | Detectable in saliva (estimated) |
|---|---|
| Alcohol | 12 to 24 hours |
| Cannabis/marijuana | 24 to 48 hours |
| Cocaine | 3 days |
| Codeine | 24 to 48 hours |
| Ecstasy | 2 days |
| Fentanyl | 24 to 48 hours |
| Heroin | 5 hours |
| Hydrocodone | 24 to 48 hours |
| Methadone | 2 days |
| Morphine | 4 days |
| Nicotine | 5 days |
| Oxycodone | 3 days |
Urine tests are usually able to detect substances that were used further back, but there are more challenges to testing including the risk of urine samples being manipulated. This can include people adding substances to the urine sample or submitting other people's urine for testing.
Legal Considerations
If you work in an industry related to transportation, national safety, or public safety, you may be required by law to undergo regular drug testing. These include jobs regulated by the Department of Transportation.
Depending on the regulations, people who test positive may be directed to a substance abuse program (which means you may not be immediately dismissed for having tested positive).
Laws for other industries vary by state. Testing oral fluids via a mouth swab is not allowed in Hawaii, Maine, Puerto Rico, and Vermont.
Most other states allow the use of oral swabs for employee drug testing, albeit with limitations and restrictions. To find out about the laws in your state, contact the American Civil Liberty Union (ACLU) at 212-549-2500.
Where to Find Help
If you or a loved one is struggling with an alcohol or substance use disorder, call the Substance Abuse and Mental Health Services Administration (SAMHSA) National Helplineat1-800-662-4357for information on support and treatment facilities in your area. Know that you are not alone.
Summary
Mouth swab drug tests are a drug screening tool that uses saliva to detect various substances in your system. These tests are painless and quick, sometimes delivering results in minutes. Mouth swab tests are usually best for detecting recent drug use. Mouth swab drug tests are typically used to detect alcohol, amphetamines, cocaine, marijuana, opioids, and more.
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Verywell Health 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.
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By Molly Burford
Molly Burford is a mental health advocate and wellness book author with almost 10 years of experience in digital media.
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