Cannabis urine detection time
A urine immunoassay screens for THC-COOH, the main metabolite of delta-9 THC. After one use, THC-COOH leaves urine in about 3 days. After daily use for months or years, it can stay for 30 days or more. Body fat, dose, potency, and metabolism set the exact number. No home method shortens the window in a reliable way.
What the test measures
Labs run an immunoassay screen first. Federal workplace guidelines set the screen cutoff at 50 ng/mL. A sample that screens positive goes to GC-MS or LC-MS/MS confirmation at a 15 ng/mL cutoff. THC-COOH is fat-soluble. It moves from blood into fat tissue, then back into blood over days and weeks. Urine carries it out of the body.
How Long Can Cannabis Be Detected in Urine?
Detection windows by use pattern
- One-time use: 1 to 3 days
- Use 2 to 4 times per week: 5 to 10 days, sometimes 14
- Daily use: 10 to 30 days
- Heavy daily use, high-potency concentrates, long history: 30 to 90 days in some cases
These ranges come from controlled studies with small samples. Individual results vary.
What moves the window
- Frequency and dose: more THC intake means more stored metabolite.
- Potency: vape oils and concentrates carry 60% to 90% THC. Flower ran about 4% THC in the 1990s. Modern flower runs 15% to 30%.
- Body fat: THC-COOH binds to fat tissue. Higher fat mass can extend release.
- Metabolism and age: liver enzyme activity and age change clearance.
- Hydration: dilute urine drops creatinine. Labs flag samples with creatinine below 20 mg/dL as dilute. A dilute sample counts as a refusal or a negative, depending on the panel. It does not erase the metabolite.
CBD products and THC
CBD isolate holds no THC. Full-spectrum CBD holds THC at 0.3% or less by dry weight under US law. A 30 mL bottle of full-spectrum oil at 2 mg THC per mL delivers 60 mg of THC across the bottle. Daily use of that product can build THC-COOH in the body. Third-party lab reports (COAs) list THC content per batch. Check the THC number on the COA before you use a full-spectrum product and expect a urine test.
Cannabis in Urine: How Long Does It Stay?
Test cutoffs
The 50 ng/mL screen catches most recent use. Some labs run a 20 ng/mL screen. Lower cutoffs extend the detection window. A 15 ng/mL confirmation cutoff can find metabolite weeks after a 50 ng/mL screen turns negative.
What does not work
Water loading, vinegar, niacin, creatine, and commercial detox drinks have no clinical evidence for a negative result. Water loading can trigger a dilute flag. Niacin at high doses causes liver injury. Labs test for pH, specific gravity, creatinine, and oxidants.