How long does cannabis stay in your system?
Detection times depend on the test. Urine tests detect THC-COOH, a metabolite. A single use of cannabis can show in urine for 3 days. Moderate use (4 times per week) can show for 5 to 7 days. Chronic daily use can show for 10 to 30 days. Some long-term users test positive for up to 45 days. One study found chronic users positive for 77 days.
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Blood tests detect THC itself. A single use shows for 1 to 2 days. Chronic use can show for up to 7 days.
Saliva tests detect THC. A single use shows for 1 to 3 days. Oral fluid tests have a window of 24 to 72 hours.
Hair tests detect THC-COOH. Hair grows about 0.5 inches per month. A hair test can detect cannabis for up to 90 days. The test requires a hair sample of 1.5 inches.
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Factors that change detection time
- Frequency of use: daily use lengthens the window.
- Dose and potency: higher THC doses lengthen the window.
- Body fat: THC stores in fat tissue. Higher body fat can extend release.
- Metabolism: faster metabolism clears THC faster.
- Hydration: dilution can lower metabolite levels. But it does not change the detection window.
- Exercise: fat breakdown can release THC. This may raise levels before a test.
- Age: older adults clear THC slower.
Drug test cutoffs
Federal urine tests use a two-step process. The immunoassay screening cutoff is 50 ng/mL for THC-COOH. The confirmation cutoff is 15 ng/mL by GC-MS or LC-MS/MS. A positive result requires both steps. Some employers use lower cutoffs. Point-of-care tests may use 20 ng/mL or 50 ng/mL.
Test type summary
- Urine: 3 days (single use) to 30 days (daily use).
- Blood: 1 to 2 days (single use) to 7 days (daily use).
- Saliva: 1 to 3 days.
- Hair: up to 90 days.
No method removes THC from the body faster. Water, exercise, and detox products do not change the detection window. They can cause diluted samples. Diluted samples may be rejected as invalid.