Short answer
Urine tests do not look for THC. They look for THC-COOH, a metabolite made in the liver. Detection time depends on how much THC-COOH sits in the body and how fast the body clears it.
can-secondhand-smoke-make-you-fail-a-drug-test
Standard windows:
- One use: 1 to 3 days
- Weekly use: up to 7 days
- Daily use: 15 to 30 days
- Heavy long-term use with high body fat: 30 days or more
Federal workplace guidelines set the screening cutoff at 50 ng/mL and the confirmation cutoff at 15 ng/mL. A lower cutoff makes the window longer.
marijuana detox timeline by test type
Frequency and dose
Each session adds THC-COOH to the pool. Daily users start the next session before the last one clears. Concentrates and edibles deliver larger doses than smoked flower, so they add more metabolite per session.
Marijuana Detox Timeline by Test Type
Body fat and BMI
THC is fat soluble. It moves into adipose tissue and leaves over weeks. People with higher body fat percentages tend to test positive longer. Weight loss and fasting release stored cannabinoid into blood.
Metabolism
Liver enzymes CYP2C9 and CYP3A4 handle THC. Genetic variants that slow these enzymes extend clearance. Age, liver function, and other drugs that compete for the same enzymes also change the rate. Women can show longer windows than men at the same dose in some studies.
Hydration and dilution
Drinking water lowers THC-COOH concentration and creatinine. Labs flag samples with creatinine below 20 mg/dL as dilute. Dilution can drop a sample under 50 ng/mL for a few hours. It does not change how fast the body clears the metabolite.
Exercise
Strenuous exercise before a test can raise urine THC-COOH in chronic users. The rise comes from fat breakdown, not from new use.
Route of use
Inhaled THC peaks in blood in minutes. Oral THC peaks in 1 to 2 hours and delivers a larger fraction to the liver. Higher dose means a longer window. Route changes the peak, not the total clearance time.
Test cutoff and assay
A 20 ng/mL cutoff extends the positive window compared with 50 ng/mL. Point-of-care strips vary by brand. Labs confirm positives with GC-MS or LC-MS/MS at 15 ng/mL.
What does not work
- Niacin, vinegar, bleach, and retail detox drinks have no evidence of changing THC-COOH clearance.
- Creatine loading can hide a dilute sample on some panels. It does not remove metabolite.
No at-home method shortens the window in a consistent way. The main inputs are dose, frequency, body fat, liver enzyme activity, hydration, and the cutoff the lab uses.