Quick answer: Most drugs show on a saliva (oral fluid) test for about 24 to 72 hours after last use. Oral fluid tests detect parent drugs, such as THC, cocaine, amphetamines, opiates and PCP, at set cutoffs in ng/mL. A positive screen is preliminary and must be confirmed by GC/MS or LC-MS/MS laboratory testing, says American Screening Corp.
- Typical oral fluid window: about 1 to 3 days. Heavy or chronic use can extend it, and the window varies by person and dose.
- HHS initial cutoffs for oral fluid include THC 4 ng/mL, cocaine metabolite 15 ng/mL, and amphetamines 25 ng/mL (SAMHSA, as of November 2026).
- Every positive screen is preliminary; confirm by GC/MS or LC-MS/MS before any action.
What does a saliva drug test detect?
An oral fluid test is an immunoassay that detects drugs and metabolites in saliva collected from the mouth. It is used by clinics, treatment centers, courts, probation offices, staffing firms and employers who need observed, non-invasive collection.
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Oral fluid mostly reflects recent use because drugs pass from blood into saliva. For federal workplace programs, the Mandatory Guidelines for Federal Workplace Drug Testing Programs using Oral Fluid (HHS/SAMHSA) set the drug classes and cutoffs. Confirm the cutoffs printed on the insert of the specific device you buy, since non-federal tests may differ.
How long do drugs show on a saliva test?
Windows run from a few hours to about three days for most drugs. The table below gives commonly cited ranges alongside the HHS oral fluid initial test cutoffs.
| Drug class | Initial cutoff (ng/mL) | Typical window after last use |
|---|---|---|
| Marijuana (THC) | 4 | Up to about 24 hours after occasional use; longer with heavy use |
| Cocaine / benzoylecgonine | 15 | About 1 to 2 days |
| Amphetamine / methamphetamine | 25 | About 1 to 3 days |
| Opiates (codeine, morphine, hydrocodone, hydromorphone, oxycodone) | 30 | About 1 to 3 days |
| Heroin metabolite (6-acetylmorphine) | 3 | Hours up to about 1 day |
| Phencyclidine (PCP) | 3 | About 1 to 3 days |
| MDMA / MDA | 25 | About 1 to 2 days |
Windows are approximate ranges, not guarantees. Always rely on the device insert and your laboratory for exact figures.
What changes the detection window?
Several factors move the window shorter or longer. Buyers should know them when writing a testing policy.
- Dose and frequency: daily use lengthens detection compared with a single use.
- Drug and route: smoked, oral and injected routes clear differently.
- Cutoff level: a lower cutoff detects for longer than a higher one.
- Collection timing: oral fluid is best for recent use, so timing of collection matters.
- Individual physiology: metabolism and saliva flow vary between people.
Saliva vs urine: which window fits your program?
Oral fluid is better for recent use, such as post-incident, reasonable-suspicion or pre-shift checks. Urine generally looks back further and remains the standard specimen for many programs. If you need the longer lookback, review our drug test cups for urine screening.
For DOT-regulated testing, follow 49 CFR Part 40 from the Department of Transportation, which governs specimen types, collection and the role of the Medical Review Officer. Check the current rule before choosing a specimen type.
How should you handle a positive saliva test?
Treat a positive screen as preliminary, not as proof of use. Follow this procedure:
- Record the result, the lot number and the time of collection.
- Keep the specimen sealed with chain of custody if confirmation is required.
- Send it to a laboratory for GC/MS or LC-MS/MS confirmation.
- Take no adverse action until the confirmed result is back and reviewed under your policy and state law.
Buyer checklist for oral fluid testing
- Confirm the device is FDA-cleared and CLIA-waived where required, and keep the documentation.
- Check that the cutoffs (ng/mL) match your policy.
- Define the collection window, for example no food, drink or tobacco for the period in the instructions.
- Train staff on reading results within the time stated on the insert.
- Arrange laboratory confirmation before you need it.
- Check your state statutes on workplace and oral fluid testing.
- Pair pre-hire screening with a compliant background check, such as Reveal Background.
Clinics, courts, staffing firms and distributors can ask about wholesale oral fluid and urine supplies through our contact page.
Frequently asked questions
How long does THC show on a saliva test?
THC commonly shows for up to about 24 hours after occasional use, and longer with frequent use. The HHS initial oral fluid cutoff is 4 ng/mL. Confirm any positive by GC/MS or LC-MS/MS.
Can a saliva test detect drugs from a week ago?
Usually not. Most drugs clear from oral fluid within about 1 to 3 days. For a longer lookback, programs generally use urine or other specimens.
Is a saliva drug test result final?
No. A positive screen is preliminary and must be confirmed by GC/MS or LC-MS/MS laboratory testing before any decision is made.
Are saliva tests FDA-cleared and CLIA-waived?
Many are, but status is product specific. Check the FDA clearance and CLIA waiver on the exact device and keep the paperwork on file.
Sources
- SAMHSA: Workplace Drug Testing and the HHS Mandatory Guidelines
- eCFR: 49 CFR Part 40, DOT Procedures for Transportation Workplace Drug and Alcohol Testing Programs
- CDC: Clinical Laboratory Improvement Amendments (CLIA)
This article is general information, not legal or medical advice.
