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Complete Guide To Saliva Drug Tests

A lab worker wearing gloves dips a cotton swab in a vial to complete saliva drug test for pre-employment.

Pre-employment drug screening can help you maintain a safer, more productive workplace, but the myriad of options can be overwhelming. There are oral fluid (saliva), urine, hair follicle, and blood drug testing options available to you, each with their own unique benefits and challenges.

In this article, we’ll explore the accuracy, detection period, and use cases of saliva drug tests and compare them to your other options. Then you can make an informed decision around which drug tests are best suited for your pre-employment screening.

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What Is A Saliva Drug Test?

A saliva drug test is a drug screening test that detects traces of substances in someone’s saliva to identify the presence of drugs or alcohol in their system.

A saliva drug test is also known as a mouth swab drug test, oral drug test, or cotton swab drug test.

How Does A Mouth Swab Drug Test Work?

A common collection method is to use a swabstick with an attached sponge or absorbent pad to swab the inside of the cheek or under the tongue. Other collection methods include spitting, draining, and suction to gather saliva for testing.

A mouth swab drug test may be conducted on-site, including in an office or at the scene of an accident, or at a dedicated lab or specimen collection site.

The individual being screened may be asked not to eat or drink anything for 10 minutes before the test to ensure better accuracy. Food, beverages, medication, and mouthwash can all interfere with accurate saliva drug test results.

The specimen will either be instantly analyzed on-site or sent to a lab to determine if traces of controlled substances are present in the individual’s body.

If the initial screen yields a non-negative test result, a more sensitive confirmation screening will be done at a lab and a thorough medical review may be performed for accuracy. This step is important. The person being tested may use a prescription or over-the-counter medication that has resulted in a false-positive drug test. A Medical Review Officer (MRO) may verify the medical records provided by the individual being tested, possibly contacting their pharmacy or doctor’s office for prescription verifications.

What Does A Mouth Swab Test For?

There are saliva tests that can detect a single substance, such as an alcohol or marijuana swab test, as well as multiple panel drug screenings that detect a combination of substances. These usually include common drugs of abuse such as:

  • Alcohol
  • Amphetamines
  • Barbiturates
  • Benzodiazepines
  • Cocaine
  • Marijuana
  • Methamphetamine
  • Opioids
  • Opiates
  • Phencyclidine

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How Accurate Is A Mouth Swab Drug Test?

A mouth swab drug test is relatively accurate—but only when used correctly. Mouth swabs are also typically conducted by an administrator or under supervision, making it more difficult for the person being tested to tamper with the specimen.

Accuracy can vary between instant oral fluid testing kits, instant oral fluid testing devices, and lab testing. For example, one study found that a mobile saliva test system was 97.5% accurate compared to a saliva test conducted in a lab. Accuracy may also vary by specimen collection method, drug type and concentration, and whether saliva flow was stimulated. For instance, oral fluid production agents such as citric acid candy or chewing gum have been shown to lower concentrations two- to six-fold for codeine, two- to four-fold for methamphetamine, and five-fold for cocaine.

How Accurate Is A Saliva Drug Test for THC?

Evidence suggests that THC is deposited in the oral cavity during cannabis smoking and high THC concentration can be found in saliva specimens immediately after smoking. This is followed by a rapid clearing and slower decline over 12 hours. 

Passive cannabis exposure (when a person inhales marijuana smoke from a nearby user),  on the other hand, will have negative drug test results within an hour of exposure. A positive saliva drug test for THC provides an accurate indication of active cannabis use when recent passive exposure can be ruled out.

Is A Saliva Or Urine Drug Test More Accurate? 

Urine and blood drug tests are both typically more accurate than saliva—but again, they must be used correctly. 

A study comparing urine and saliva drug tests found that urine drug testing was more likely to detect overall substance use than oral testing. Of the 12 positive drug test results, nine were identified via the urine test, one via saliva test, and two via both tests.

Urine drug tests also have a longer detection period, making them a better choice for determining someone’s historical drug use.

Mouth Swab Drug Test Detection Period

How long do drugs stay in saliva and how far back does a mouth swab go?

A mouth swab drug test detection period is generally 548 hours. By comparison, drugs of abuse can be detected in blood for one or two days and in urine for 1.5 to four days.

It can be challenging to get an exact detection period for any drug test, as controlled studies can be difficult to execute. As one researcher explains, “illicit products have to be given to healthy volunteers and doses administered are low compared with street doses.”

The detection period can also vary by factors such as:

  • The drug used
  • The quantity of the drug taken
  • The frequency in which the person being tested uses drugs
  • The duration of drug use
  • The preparation and route of drug administration
  • The metabolism of the person being tested
  • The sensitivity of the testing method used

For example, the marijuana (THC) swab test detection time is 72 hours, while heroin can only be detected for about an hour. Most other types of drugs and their detection period fall within that range, though some can be detected for much longer periods of time. For example:

  • Ecstasy and cocaine can be detected for up to two days
  • Morphine can be detected for up to three days
  • Methadone can be detected for up to 10 days

Since most substances can’t be detected in saliva for long, testing within the appropriate window of time is crucial for accurate results. For this reason, saliva drug tests are often used to identify current or recent drug use—therefore, this use case may not be ideal for testing heavy drug users. 

A study explored prolonged excretion of cocaine in saliva specimens collected from heavy cocaine users during abstinence. Researchers found that elimination of cocaine in saliva may take up to 10 days in chronic users. Cocaine has a half-life of approximately one hour, but it’s unclear if heavy use prolongs the effects of the drugs used.

How Long Does It Take For Mouth Swab Results?

Instant on-site drug testing kits and devices can provide results in just a few minutes, while results for specimens analyzed by a lab are generally available within 1–3 days.

Depending on the provider, presumptive positive screens may undergo a lab-based confirmation testing and a review process that requires 2–3 additional days.

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Saliva Drug Test Laws To Know

Employment drug screenings are regulated at the federal and state level, and it’s important to be aware of drug test laws so you can ensure compliance. These include:

  • Title VII of the Civil Rights Act of 1964. Title VII prohibits employer discrimination based on race, color, religion, sex, or national origin. This includes intentional discrimination, as well as disparate impact discrimination in which an employer’s actions result in unintended discrimination against a protected group. Drug testing must be administered fairly and consistently so you can maintain compliance. Put a screening policy in place that takes federal and local laws into consideration, and follow it so you screen all candidates for a given role in the same manner.
  • The Fair Credit Reporting Act (FCRA). The FCRA only applies when an employer uses a third-party screener to perform the drug test. It stipulates that employers provide a background check disclosure and authorization forms before screening is conducted. If an employer intends to deny or terminate employment based on a failed drug test, they must follow the adverse action process, which includes providing the candidate or employee with a copy of the background check results.
  • State laws. State laws vary, and some have imposed limitations on pre-employment drug testing. For example, an employer in California may only require a drug test as a condition of employment after a job offer is extended. Employers should be aware of their state’s laws before implementing a drug testing program.

Always consult with your legal counsel if you have questions about drug tests as part of your employment screening program. 

Pro & Cons Of Saliva vs Urine, Hair Or Blood

Administration & Turnaround TimesSaliva:
Quick, easy, non-invasive, and painless.
On-site testing results are available in minutes. Lab testing turnaround times are 2–3 days.
Most invasive, may be painful to the individual.
Turnaround times are one week.
Quick, easy, and painless.
Turnaround times are 2–3 days.
Quick, easy, and painless. Hair length may affect consistent screening practices.Turnaround times are up to one week.
CostSaliva: Low costBlood: High costUrine: Low costHair: High cost
Short, immediate detection period. 
Able to detect recent drug use, but not historic drug use. Short-term abstinence can hinder detection.
Short detection period.
Able to detect current or recent drug use, but not historic drug use.
Longer detection period.
Able to detect historic drug use and some recent drug use.
Longest, widest detection period.
Able to detect historic drug use, but not recent or sporadic drug use.
Less accurate than urine or blood.
Specimen collected by administrator  or under supervised observation and therefore more difficult to tamper with.
Highly accurate.
Specimen collected by administrator and therefore more difficult to tamper with.
Highly accurate.
Unmonitored collection may allow for specimen tampering.
Most accurate.
Specimen collected by a trained collector, and therefore more difficult to tamper with.

How To Get A Saliva Drug Test

There are three ways to get a saliva drug test:

  1. Instant oral fluid testing kits
  2. Instant oral fluid testing devices
  3. Lab testing

The easiest way is to use a compliant screening provider and include drug tests in your background checks. This can help you build a fair, consistent drug screening practice that helps you make more informed decisions and maintain compliance.

Choose The Right Type Of Drug Screening For Your Needs

Saliva is just one type of drug test often used for specific circumstances such as random, reasonable suspicion, or post-accident testing. They’re not designed to tell you if a person uses drugs—only if they’ve used drugs recently. This may be problematic in pre-employment drug screening, particularly if a candidate briefly abstains from recreational drug use while they interview. Urine is typically a better specimen choice to screen for prior drug use, while hair can help you detect long-term drug abuse.

GoodHire’s employer drug screening offerings are designed to meet your company policy and drug-free workplace obligations, while helping you maintain compliance with applicable regulations. Lab-based urine tests are available with multiple panel options and lab results are verified by Medical Review Officers (MROs) for highest accuracy. Drug screening results are easy to review in the GoodHire dashboard. For more details, talk to sales.

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The resources provided here are for educational purposes only and do not constitute legal advice. We advise you to consult your own counsel if you have legal questions related to your specific practices and compliance with applicable laws.

About the Author

Jen Dewar

Jen Dewar is a marketing consultant in the HR technology space with a focus on developing educational content for HR professionals and recruiters. She is passionate about diversity and inclusion, lifelong learning and development, and treating people like people throughout the candidate and employee experiences.