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Drug Toxicology Monitoring, Oral Fluid Testing

Test code(s) 36862, 93975, 93976, 93977, 93978, 93979, 93980, 93981, 93982, 93983, 93984, 93974, 93985, 93986, 93987, 93988, 93990

Oral fluid is the liquid material collected from within the oral cavity of the mouth and is comprised of saliva (from submandibular, sublingual, and parotid glands), gingival crevicular fluid (from between teeth and gums), cellular debris, bacteria, and food residues.

Oral fluid drug testing is an alternative to urine drug testing. Results are similar to those obtained from urine drug testing but differ in 2 important ways. First, drugs are detectable sooner in oral fluid than in urine. Drugs enter the bloodstream and are transported throughout the body. Once the blood reaches the salivary glands, drugs rapidly enter the oral fluid. This takes less time than the time taken for drugs to enter urine. Second, drugs are cleared from oral fluid faster than they are cleared from urine. Thus, the oral fluid “detection window” for some drugs such as cocaine and heroin can be as little as a few hours. However, most drugs remain detectable in oral fluid for 24 to 50 hours after use.1

Quest Diagnostics offers multiple options for oral fluid drug testing. These include

  • Multi-class drug panels for presumptive analysis with reflex to definitive confirmation and quantitation
  • Single-class drug tests for presumptive analysis with reflex to definitive confirmation and quantitation 

Liquid chromatography-tandem mass spectrometry (LC-MS/MS) is used for both the presumptive analysis and the definitive confirmation and quantitation.

Drug classes, compounds, and assay cutoffs for detection are listed in the table below.

Table showing drug classes, compounds, and assay cutoffs for detection

(click to open larger image in new tab)

Urine is the most widely used and well-established sample type at present and offers the broadest options for drug testing. However, urine-based drug testing has several potential drawbacks including inconvenience and patient embarrassment, sample integrity problems when collection is not observed, and lack of privacy when specimen collection must be observed.

The main advantage of oral fluid testing is the ease of observing sample collection, while the disadvantages relate to shorter drug detection windows, lower drug concentrations in the sample, and limited specimen volume. The decision to use oral fluid drug testing should take into account the potential benefits and drawbacks of this matrix as they apply to individual clinical scenarios. 

The preferred specimen is a properly collected Quantisal™ device (1 mL oral fluid inserted into a 3-mL buffer tube). 

Rejection criteria include

  • Specimens submitted in a non-Quantisal collection device
  • Specimens received with any food debris or foreign objects present in the sample
  • Multiple swabs present in a single device
  • No swab present in the device
  • Specimens received with the Quantisal collection wand inverted inside the collection tube

Negative results indicate absence of drug and/or metabolite or concentrations below the assay cutoff. Positive results indicate presence of the respective drug and/or metabolite. Detection of drug(s) or drug metabolite(s) suggests that the patient has taken the drug(s). The concentration of drug and/or metabolite in the oral fluid does not indicate time of dose or dose taken.

Yes. Oral fluid drug testing is considered a clinical test; therefore, multiple clinical specimens from one patient may be placed in the same bag. However, specimens from another patient should be placed in a separate bag.

For any questions regarding this information or assistance with interpreting these drug test results, please contact a Quest toxicology specialist at 1.877.40.RX TOX (1.877.407.9869). Specialists are available to assist you Monday through Friday from 8 AM to 10 PM ET.


  1. Verstraete AG. Detection times of drugs of abuse in blood, urine, and oral fluid. Ther Drug Monit. 2004;26(2):200-205. doi:10.1097/00007691-200404000-00020 

This FAQ is provided for informational purposes only and is not intended as medical advice. Test selection and interpretation, diagnosis, and patient management decisions should be based on the clinician’s education, clinical expertise, and assessment of the patient.

Document FAQS.186 Version: 3

Version 3: Effective 04/03/2023 to present

Version 2: Effective 02/20/2023 to 04/03/2023

Version 1: Effective 12/5/2018 to 02/20/2023
Version 0: Effective 05/22/2017to 12/5/2018