The Mouth Swab Drug Test and Employment (Guest Post)

The mouth swab drug test is commonly used by employers.

Many companies require their employees to take drug tests. If your dream job is to join the military, work for the government, or even be employed at a hospital, you should definitely expect to be tested.

Failing drug tests usually guarantees a job termination (or being turned down for a prospective job). With something this big at stake, it is crucial to be well-versed on drug-testing, particularly if you use cannabis for medical or other purposes.

This article is about the mouth swab test (MST), which is one of the most commonly used by employers.

What is a Mouth Swab Drug Test?

The MST is also known as a saliva or oral fluid test. As you can guess from the name, the test is taken by taking samples of a person’s saliva.

The MST can detect if the test taker has recently used marijuana, amphetamines, cocaine, alcohol, or methamphetamines. Many companies prefer the MST over other tests because it is inexpensive. It is also fairly quick and takes minimum effort to process.

List of Commonly Indicated Drugs for MST

According to the Substance Abuse and Mental Health Services Administration (SAMHSA) guidelines, the drugs listed below qualify for the mouth swab drug testing:

  • Marijuana, Cannabinoids, Hash
  • Angel Dust, PCP
  • Codeine, Morphine, Heroin, Opium
  • Crack, Coke
  • Ecstasy, Crank, Speed, Meth
  • Alcohol
  • Quaaludes
  • Xanax, Librium, Valium
  • Butalbital, Phenobarbital, Downers, Secobarbital
  • Darvon compounds
  • Methadone
  • Peyote, Mushroom, LSD, MDMA, Mescaline
  • Anabolic steroids
  • Oxycodone, Vicodin, Lortab

Usage Timeframes and Detectability

Some drugs can stay in the body for a few hours, while some can take weeks to leave the body. The list below provides a very general timeframe for how long drugs typically remain in the human body at detectable levels:

  • Marijuana: A week to several weeks
  • Heroin: 1 to 3 days
  • Amphetamines: 2 to 5 days
  • Methamphetamine: 2 to 4 days
  • Alcohol: 12 to 48 hours
  • Cocaine: 2 to 10 days
  • Methadone: 1 to 3 days
  • Phencyclidine (PCP): 1 to 2 weeks
  • Benzodiazepine: 1 to 4 days
  • Oxycodone: 1 to 2 days
  • Barbiturates: 1 to 3 weeks

What if You Are Taking Prescription Medication?

If you are taking prescription medication for a health condition it is usually best to disclose this information confidentially to the test taker before taking the MST. Failing to do so may cause a test failure and consequent termination or administrative hassle.

Types of Employment Drug Tests

There are various situations for which you may be required to provide a sample for a drug test for your employer. These include:

  • Pre-Employment Screening Drug Test. Depending on the state in which you live, you may be required to take a drug test before joining a company. We recommend consulting with an attorney to understand your state’s laws.
  • Random Drug Test. A company may choose to test its employees for drug abuse randomly and without prior notice. Employees are often selected for drug testing by an electronic lottery pool.
  • For Cause Drug Test. Depending on company policy and state laws, a company may require an employee to provide a sample for drug testing when the employer has cause to believe that an employee is, or was, under the influence of drugs while working. Common reasons to require for cause drug testing include frequent tardiness, absences, and poor job performance. Employees who refuse to take a drug test may be subject to disciplinary actions or even termination.
  • Post-Accident Drug Test. A post-accident drug test is conducted after an employee has been injured at work due to an accident. This is to determine whether the employee was under the influence at the time of the accident. In addition to being a factor in deciding whether an employee should be disciplined for the accident, it can also be required for worker’s compensation and other insurance claims.

Benefits of Mouth Swab Drug Testing

Mouth swab drug testing is an easy, convenient, and painless way to test for substance abuse. It involves collecting samples of an individual’s saliva with a swab for testing. The test takes about five minutes overall, and the results are usually available within two days. The results are instant and do not involve laboratory verification.

Disadvantages of Mouth Swab Drug Testing

The MST’s primary disadvantage is that it is not able to determine whether a person is engaged in the habitual use of drugs. It only measures whether certain compounds are in a person’s body.

Second, cough medicines such as codeine can affect the results of the mouth swab drug test. Recent ingestion of sufficient quantities of cough syrup can trigger a positive result for opiates.

Third, people who suffer from persistent dry mouth may not be able to produce enough saliva for the test. These people have to take other forms of test to pass the employment screening process.

Fourth, cannabinoids derived from hemp, such as cannabidiol (CBD), may be indicated by the MST and trigger a “false positive” result for marijuana use.

Limitations of the Mouth Swab Drug Test

As stated above, the MST’s primary limitation is its inability to detect habitual drug use. For this reason, it is generally easy to pass an MST, particularly for cannabis and alcohol use, if the person who is to take it has enough advance notice. With notice, the test taker can abstain from use for a period of time. Additionally, detoxification is a commonly used strategy for passing a drug test. This involves drinking lots of water, coffee, lemon and cranberry juice, and frequent teeth brushing.


It is dangerous for employees to be performing at work under the influence of drugs. Mistakes can be more likely and/or frequent and can be disastrous for the company. This is one of the primary reasons that companies test their employees. The MST is the simplest, cheapest, and easiest drug test. For this reason, it is one of the most commonly used by employers.

March 16, 2018

This is a guest post by Dave of  THC He is an avid traveler, loves surfing and the natural way of life.

Rod Kight is an attorney who represents lawful cannabis businesses. He speaks at cannabis conferences across the country, drafts and presents cannabis legislation to foreign governments, is regularly quoted on cannabis matters in the media, and maintains the Kight on Cannabis legal blog, where he discusses legal issues affecting the cannabis industry. You can contact him here.

4 comments on “The Mouth Swab Drug Test and Employment (Guest Post)Add yours →

  1. To whom this may concern, my son went in for a new job offer today had a physical and orientation that he passed. Later was given a swab test that tested for a variety of dugs one being THC which came out positive. He told them that was wrong so they did it again and again tested positive. They told him he could not be hired at this time because of it. He was so upset and couldn’t understand what happened. He then went to Walmart and bought a urine test strictly for marijuana, because he could not figure out how he could have come in contact with THC and that urine test was negative. So my question is how is this possible? These tests are not accurate and cost him a job. This is affecting his life. This is not right!

    1. Jocelyn- Thank you for sharing your son’s story. Unfortunately, your son’s story is fairly common and this is an unresolved issue and there are not many regulations regarding the use of mouth swab drug tests. -Rod

  2. I just went through the same thing. I went to a pre-application ‘swab’ and it came back as positive! I do not smoke marijuana! I did write a letter to dispute the test results but dont think would be much. I also did the otc test and was negative…I dont like that I was put through this FALSE TEST! That’s my name and career on the line…There should be better test or the test places responsible for proper testing equipment! I have heard of this happening to others in my area of work…not right!…

Leave a Reply

Your email address will not be published. Required fields are marked *