How long does cannabis stay in your system for a drug test?

Detection times depend on the test. Urine tests find THC for 1 to 30 days. Blood tests find THC for 1 to 7 days. Saliva tests find THC for 1 to 3 days. Hair tests find THC for up to 90 days.

what does a cannabis drug test detect

Urine test

  • One-time use: 1 to 3 days.
  • Use several times a week: 3 to 7 days.
  • Daily use: 10 to 30 days.
  • Heavy long-term use: 30 to 60 days.

Urine tests look for THC-COOH, a metabolite. Body fat stores THC metabolites. People with more body fat clear them slower.

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Blood test

Blood tests measure THC itself, not just metabolites. THC leaves blood fast. Occasional use is detectable for 1 to 2 days. Heavy use is detectable for up to 7 days. A blood test is common for DUI cases because it shows recent use.

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Saliva test

Saliva tests use oral fluid. One-time use is detectable for 24 hours. Regular use is detectable for 1 to 3 days. Saliva tests are common at workplaces and roadside stops.

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Hair test

Hair tests have the longest window. THC enters hair through blood flow. A standard test uses 1.5 inches of hair. That length covers 90 days. THC shows up in hair about 7 to 10 days after use. Hair tests do not show when or how often a person used.

What changes the detection window

  • Frequency of use. Daily use builds up THC metabolites.
  • Body fat. THC is fat-soluble. More fat means slower release.
  • Metabolism. Faster metabolism clears THC faster.
  • Hydration. Water does not flush THC. It only dilutes urine for a short time.
  • Test sensitivity. Labs have different cutoff levels. A 50 ng/mL cutoff is common for urine screening. A 15 ng/mL cutoff is common for confirmation.

CBD products and drug tests

CBD does not cause a positive THC test. Full-spectrum CBD can contain THC. The legal limit is 0.3% THC by dry weight. Repeated use of full-spectrum CBD can build up THC metabolites. A urine test may detect them. CBD isolate has no THC. Check lab reports before you buy.

Key numbers

Urine: 1 to 30 days. Blood: 1 to 7 days. Saliva: 1 to 3 days. Hair: up to 90 days. These are ranges. Individual results vary.