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How Far Back Does A Mouth Swab Drug Test Go?

Whether you’re faced with a need to pass a pre-employment mouth swab drug test, a random drug test at work, or a post-incident drug test, the process will undoubtedly cause a certain amount of anxiety for anyone who uses drugs recreationally.

And for medical marijuana users, the results of a drug test could lead to trouble, even in states where medical marijuana is now legal.

By knowing how far back does a mouth swab drug test go, you will be able to plan for your pre-employment drug test. And for those faced with a spot test, knowing about the mouth swab drug testing limitations could save you from days of needless anxiety.

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What Is A Mouth Swab Drug Test?

What Is A Mouth Swab Drug Test?

A mouth swab drug test is a noninvasive drug test used by many employers for pre-employment drug screenings as well as for random drug tests and post-incident or accident drug screens.

For this type of drug test, a saliva sample is collected and then analyzed for the most common recreational drugs.

When you present for a mouth swab drug test, you will be asked to refrain from eating or drinking for 10 minutes. This is because food and drink can be used to adulterate your saliva in an attempt to cheat the test.

After 10 minutes, the technician will swab inside your mouth with a long cotton Q-Tip type swab or will ask you to swab your own mouth.

Once the sample is collected, it is placed inside a container with a preservative. The sample will then be analyzed on the spot or sent away for laboratory analysis.

Which Drugs Does A Saliva Test Detect?

The most common drug saliva test is a standard 5-panel test which will screen for:

  • Opiates
  • Cocaine
  • Marijuana
  • Amphetamines and Methamphetamine
  • Phencyclidine (PCP)

Some mouth swab tests do a more thorough screening called an extended screening or a 10-panel screen, and this test looks for the substances on the 5-panel test as well as these additional substances:

  • Alcohol
  • Benzodiazepines
  • Methadone
  • Oxycodone
  • Buprenorphine-Suboxone

Other saliva mouth swab tests look for single substances. Usually, these are tests that look for marijuana use or for alcohol consumption.

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How Far Back Does A Mouth Swab Drug Test Go?

How Far Back Does A Mouth Swab Drug Test Go?

A mouth swab saliva test can detect recent drug use and doesn’t detect drug use as far back as a urine test.

For the substances tested on the 5-panel and 10-panel drug screen, the detection periods are as follows.


(Street names include – China White, Dope, Skunk, Smack, Cody, Morpho, and Brown Sugar).

Opiates include commonly abused substances like heroin, morphine, and codeine. The detection window given collectively for these drugs is usually 36 – 48 hours, but morphine may be detected for up to 3 days depending on the level of use.

Amphetamines & Methamphetamine

(Street names include – Meth, Cookies, Ice, Scooby Snacks, Speed, Rocket Fuel, and Tweek).

These substances can be detected with a saliva drug test for up to 48 hours after use.


(Street names include – Oxy, Hillbilly Heroin, Kicker, Roxy, and Perc).

Oxycodone is a synthetic opiate and can be detected for up to 48 hours.


(Street names include – Charlie, Crack, Snow, White Girl, Batman, and Columbia).

Cocaine can be detected for up to 48 hours since the last use with a mouth swab test.


(Street names include – Bud, Hash, Grass, Mary Jane, Herb, Pot, Weed, and Roach).

A standard time frame given for the detection of THC metabolites is 24 – 48 hours, but this is only true for light users.

Heavier users will have a much higher level of THC metabolite stored in their fat tissue, which needs to be processed before it can be eliminated from their bodies.

Another factor you must take into account is your body fat level. Lean individuals have less fat to act as a storage site, while overweight individuals have the ability to hold on to THC metabolites for much longer.

Frequent users of strong strains of marijuana, with a high body mass index, can still fail a mouth swab drug test several weeks after their last use of the drug.

You should know that even in states where marijuana has been legalized, employers may still have zero drug policies in place, which prohibit intoxication with this substance at the workplace.


(Street name PCP, Angel Dust, Purple Rain, Zombie, Dust, Yellow Fever).

Phencyclidine can usually be detected for up to 48 hours with a saliva test.


(Street names include – Benzo’s, Candy, Tranks, Vallies, and Xannies).

Benzodiazepines include drugs like Xanax (alprazolam), Valium (diazepam), Ativan (lorazepam), and midazolam.

These are commonly prescribed for anxiety disorders and you should present a doctor’s prescription if you take any of these drugs for a medical condition.

These drugs are tested for because they are commonly abused, and without a prescription, you will have no valid reason for these substances being in your system. Benzodiazepines remain detectable for between 5 to 10 days.


(Street names include Dollies, Mud, and Red Rock).

Methadone can be picked up on a mouth swab test for up to 2 to 3 days. If you have a legitimate prescription for methadone as part of a drug addiction treatment program, you cannot lose your job for testing positive for methadone.


(street names – Buse, Sobos, Strips, Oranges).

Buprenorphine-Suboxone remains detectable in saliva for up to 3 days.


Alcohol can be detected by a saliva drug test for between 12 and 24 hours. 12 hours is the usual limit unless you were heavily intoxicated.

Is A Mouth Swab Drug Test Accurate?

Is A Mouth Swab Drug Test Accurate?

Mouth swab drug tests have a high accuracy rate but they aren’t as accurate as urine tests and may be unable to detect low levels of drug metabolites.

Mouth swab saliva tests also have a shorter detection period than urine tests, and can only reliably ascertain current drug use.

A study that investigated the accuracy of roadside saliva sample drug tests by comparing the results with laboratory saliva analysis, found that for amphetamines including methamphetamine, benzodiazepine, and cocaine the accuracy was 100% for sensitivity and specificity.

For marijuana, the accuracy level was 97.5% with a specificity of 100% and a sensitivity of 90%.

The accuracy of mouth swab saliva drug tests also depends on the person performing the sample collection. Drug testers should have appropriate training and should follow the correct procedures at all times to ensure that the drug test is fair and doesn’t violate civil rights laws (see below).

How Long Does It Take To Get The Results Of A Mouth Swab Drug Test?

A mouth swab drug test can be completed on-site or your sample may be sent away to a laboratory for analysis.

If your testing center or employer analyzes your sample on-site, the results will be ready within a couple of minutes.

When your saliva sample is sent away for laboratory analysis, you could hear about your drug test results as soon as 24 hours later, or it could take up to a week, and if the lab is very busy up to 3 weeks.

21 days is the limit at which saliva tests remain viable for testing unless the sample has been frozen.

In cases where a sample returns a positive result, a confirmatory analysis will need to be done and that will add a little extra waiting time.

Laws Governing Drug Tests

Drug tests are governed by:

  • The Civil Rights Act of 1964, Title VII, states that drug testing must be administered fairly and that a drug testing policy that follows federal and local laws must be in place.


  • The Fair Credit Reporting Act (FCRA) states that employers using third-party screening agencies must inform employees and job applicants before a drug test is carried out. And that consent must be obtained. For employees, this consent will have been obtained when you first began work and accepted company policies.


Mouth swab drug tests are a convenient and inexpensive way for employers to screen job applicants and current employees for drug use.

These tests can be used for pre-employment screenings, random drug tests, reasonable cause drug tests, and post-incident drug screens.

Most substances screened for will be detectable on a mouth swab drug test for up to 48 hours, but marijuana may remain detectable in saliva for much longer with heavy use.

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