What Is a Mouth Swab Drug Test?

Definition & Examples of a Mouth Swab Drug Test

Mouth swab drug test detect marijuana, alcohol, opioids and other drugs.

Melissa Ling / The Balance

A mouth swab drug test uses saliva to test for the presence of drugs and alcohol. Employers sometimes use these tests because they're quick and easy to administer.

Read on for more information on what a mouth swab drug test is and how you can respond to your employer when asked to take this test.

What Is a Mouth Swab Drug Test?

A mouth swab drug test collects saliva from inside a person's mouth. The saliva is sent to a lab for testing. While there are instant-read mouth swab drug tests on the market, employers don't typically use these tests because they aren't included in the Oral Fluid Mandatory Guidelines released by the Substance Abuse and Mental Health Services Administration (SAMHSA). Federal employers are required to follow the guidelines, and many private employers follow the guidelines as well.

  • Alternate names: Oral fluids test, saliva test

How Do Mouth Swab Drug Tests Work?

Mouth swab drug tests can detect drugs used within the past few days. Saliva can be tested for alcohol, marijuana, cocaine, amphetamines, and methamphetamine.

Mouth swab drug tests are popular with employers because they are less expensive than other drug tests. Saliva is also easy to collect and test, so this is the simplest and least invasive type of drug testing. Often, the tests can be done on-site, which makes them efficient. 

Mouth swab drug tests detect several substances. Some tests check for more substances than others, but employers commonly check for marijuana, cocaine, opioids, amphetamine, methamphetamine, and PCP.

Mouth swab tests are used to assess current or recent substance use. They can typically detect substances shortly after they are used and for 24 to 48 hours after use.


Substance detection windows vary depending on the substance being used, how frequently the substance is used, and how much was used.

When Are Mouth Swab Drug Tests Required?

A variety of companies use oral drug tests. Some companies have a testing policy that explains how and when applicants and employees may be tested for illegal drug use.

Some industries, including transportation and safety, may be required by law to test employees. Many federal positions require drug testing.

Policies regarding drug testing vary from state to state. For example, some states have limits as to when and how drug screening can be conducted, and others have restrictions on what circumstances can prompt employers to test for drug or alcohol use. Look up your state’s policy if you are unsure.

Federal laws such as the Drug-free Workplace Act of 1988 are designed to target workplace substance use. They legally require some employers to take action against drug use in the workplace, such as by developing a written policy. Some industries, including transportation, defense, and aviation, are required to test some applicants and employees for drug use.

When Do Employers Use Mouth Swab Drug Tests?

There are a few common times that employers conduct mouth swab drug tests. Sometimes, these are pre-employment tests, meaning they are done right after you're offered the job. This drug test will be part of the larger employment screening process, which might involve various other background checks.

Oral drug tests may also be conducted before a promotion. Your offer of the promotion might be contingent on whether you pass the test.

Some companies conduct random oral drug tests, in which they select a pool of employees to take the test. Typically, there is little advance notice for these drug tests. Employers generally have to inform employees that random drug tests are possible.

Companies may also conduct for-cause drug tests. If an employer thinks an employee may be under the influence of drugs (due to regular absences, lateness, poor performance, etc.), they can require the employee to submit an oral drug test.

Some employers also conduct these tests after an on-the-job accident or injury. This might include a car accident or an accident involving operating machinery. These drug tests help the employer decide who is liable for the accident.


Mouth swab drug tests can detect drugs sooner than urine tests, but urine tests can detect substances for a slightly longer timeframe.

Do I Have to Take a Mouth Swab Drug Test?

An employer cannot force an employee or job candidate to take an oral drug test. However, there will likely be negative consequences for refusing a test. If you refuse to take a pre-employment oral drug test, an employer can revoke a job offer. If you refuse to take a drug test while you are a current employee, your company can fire or suspend you or refuse you a promotion.

If you take an oral test but believe the results are inaccurate, you may be able to have another test or have the specimen reviewed again. Check with your company for information on how you can request a retest.

You can ask your company about its drug testing policy as well. Typically, the policy should be clearly laid out in an employee handbook. If this is not the case, you can talk to someone in human resources for more information on company policies.

Key Takeaways

  • A mouth swab drug test uses saliva to test for the presence of drugs and alcohol. 
  • Mouth swab tests can detect drugs from soon after ingestion to 24 to 48 hours after use. 
  • Drug testing policies vary from state to state and from industry to industry. 
  • Employers use drug tests to screen applicants, ensure a drug-free workplace, and determine who is at fault in workplace accidents. 
  • There may be negative consequences if you refuse a drug test. 
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  1. DISA. "Employer Impact of SAMHSA's New Oral Fluid Guidelines." Accessed June 14, 2020.

  2. Drug and Alcohol Testing Industry Association. "Workplace Drug Testing." Accessed June 14, 2020.

  3. The Clinical Biochemist Reviews. "Drug Testing in Oral Fluid." Accessed June 14, 2020.

  4. Quest Diagnostics. "Why Oral Fluid Drug Testing?" Accessed June 14, 2020.

  5. Journal of Forensic Research. "Times of Detection of Drugs of Abuse in Saliva: Study of Arrested Population," Page 3. Accessed June 14, 2020.

  6. ACLU. "State-By-State Workplace Drug Testing Laws." Accessed June 14, 2020.

  7. SAMHSA. "Federal Contractors and Guidelines." Accessed June 14, 2020.

  8. SAMHSA. "Considerations for Safety- and Security-Sensitive Industries." Accessed June 14, 2020.

  9. Nolo. "Laws on Employee Drug Testing." Accessed June 14, 2020.

  10. Quest Diagnostics. "Frequently Asked Questions." Accessed June 14, 2020.

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