Mouth Swab Drug Test: Uses, Accuracy, and More

A mouth swab drug test is used to check if you have substances in your system, such as alcohol, marijuana, or cocaine. The test is performed using an oral swab that collects a sample of saliva. Results can be returned within minutes with a relatively high level of accuracy.

Mouth swab drug tests can be used in a variety of settings, such as workplaces, probation offices, and rehabilitation facilities.

This article explains how a mouth swab drug test works, what substances they can detect, and what to expect if you are asked to undergo one. It also describes how long substances are detectable in your system and your legal rights if an oral drug test is requested.

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How Does a Mouth Swab Drug Test Work?

Most mouth swab drug tests check for multiple substances. The kit includes a small plastic receptacle with up to 12 test strips visibly seen on the front of the device. Inside the receptacle, attached to the lid, is an oral collection swab with a sponge tip.

To perform an on-site mouth swab drug test:

1. The tester will check that you have not had any food or drink for at least 10 minutes before taking the test.
2. The lip of the receptacle is removed to obtain the collection swab.
3. You will be given the swab and asked to run the tip along your cheeks, gums, and tongue for up to three minutes.
4. The tester will take the swab and place it back inside the receptacle.
5. The swab will deliver saliva to each test strip. Color changes will indicate if the test is positive (meaning that the specific substance was detected) or negative (meaning that the specific substance was not detected).
   

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 and mouthwash need to be avoided at least 10 minutes before the test to ensure that the results are not tainted.

When Is the Test Used?

Because the window of detection is relatively small, a mouth swab drug test is used on-site to determine if you recently used alcohol or an illegal substance.

Situations in which testing may be performed include:

• Pre-employment drug testing
• Probation drug testing
• Live-in drug rehabilitation facilities
• Random drug testing
• Return-to-duty drug testing (such as after a suspension)
• Post-accident drug testing
  

What Can It Test For?

Mouth swab drug tests can detect a variety of different substances, including:

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.)

Even so, 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 influence 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 Is a Drug Detectable?

There is a window by which a drug is detectable with an oral swab.

In many cases, a drug can be detected in saliva as early as one hour after a dose. Thereafter, substances like alcohol and cannabis can remain detectable from several hours to several days before gradually dropping to undetectable levels. The same is true for opiates/opioids.