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How long does THC stay in urine?

By The reference desk · Fact-checked against the cited sources

Published · Sources checked Oct 4, 2026

Short answer

A clinical review gives about 3 days after a single use, 5 to 7 days with use several times a week, 10 to 15 days with daily use, and 30 days or more in heavy long-term users. In a NIH study, one heavy user still had the metabolite in urine after at least 24 days without cannabis.

Reported detection windows for THC, by test and by how often someone uses. Ranges come from published studies, mostly of smoked cannabis. Sources checked Oct 4, 2026.
TestOnce or now and thenSeveral times a weekDailyHeavy, long-term
UrineAbout 3 days3 5 to 7 days3 10 to 15 days3 30 days or more34

What the test measures

A urine screen does not look for THC itself. It looks for THC-COOH, the inactive product the body makes from THC and clears slowly. Federal workplace rules screen urine at 50 ng/mL and send any positive screen to a second, more specific lab test with a 15 ng/mL cutoff.[1] Those rules abbreviate the metabolite as “THCA”. That is not the THCA in raw cannabis flower.

Typical windows

How often Reported window
Once, or now and then About 3 days[3]
Several times a week 5 to 7 days[3]
Daily 10 to 15 days[3]
Heavy daily use for months 30 days or more[3]

These are the ranges a clinical review in Mayo Clinic Proceedings gives for the standard screen.[3] They are typical windows, not limits: the studies below found longer tails in heavy users.

What the abstinence studies found

  • 24 days or more. NIH researchers kept 33 chronic cannabis smokers on a secure research unit for up to 30 days. In one heavy, chronic user, THC-COOH was still detectable in urine for at least 24 days after stopping.[4] The lab measured down to 2.5 ng/mL, well below the federal cutoffs, so some of those late samples may have been under a workplace test’s cutoffs.[1][4]
  • Very high levels days later. In 21 dependent users entering residential treatment, urine THC-COOH was above 1,000 ng/mL in some of them 129 hours (about 5 days) after last use, twenty times the federal screening cutoff.[6][1]

What affects the window

  • How often and how much. Regular, heavy use stretches the window the most.[3][4]
  • The cutoff. A lab that tests below the federal cutoffs will report positives for longer.[1][4]
  • The person. In people who stopped using, levels fell at very different speeds.[4][6]
  • The product does not matter once THC is in the body. Smoked hemp THCA flower, delta-9 edibles and dispensary flower all produce THC, and the body makes the same metabolite from it.

Before you rely on a number

A range from a study is not a prediction for one person. Employers and clinics may use cutoffs other than the federal ones. Only a lab test can tell you your result; questions about a result belong with the lab or the medical review officer who reported it.

Questions

What does a urine drug test look for?

THC-COOH, the inactive product the body makes from THC. Federal workplace rules screen urine at 50 ng/mL and confirm at 15 ng/mL.

Can smoked hemp THCA flower show up on a urine test?

Yes. Heat turns THCA into THC, and the body turns THC into the same metabolite the test looks for.

Is there a way to shorten the window?

This site gives no advice on changing a result. Time is the only thing that reliably lowers what a test finds; in the studies, levels fell with time since last use, at different speeds in different people.

Sources

Sources checked Oct 4, 2026. Numbers in the text link here.

  1. Substance Abuse and Mental Health Services Administration. Mandatory Guidelines for Federal Workplace Drug Testing Programs. Federal Register 82 FR 7920, January 23, 2017. www.federalregister.gov/d/2017-00979Checked Oct 4, 2026 against the full text: the cutoff table.
  2. Moeller KE, Kissack JC, Atayee RS, Lee KC. Clinical Interpretation of Urine Drug Tests: What Clinicians Need to Know About Urine Drug Screens. Mayo Clin Proc. 2017;92(5):774-796. doi.org/10.1016/j.mayocp.2016.12.007Checked Oct 4, 2026 against the citation. Editor check of the figures pending.
  3. Lowe RH, Abraham TT, Darwin WD, Herning R, Cadet JL, Huestis MA. Extended urinary Delta9-tetrahydrocannabinol excretion in chronic cannabis users precludes use as a biomarker of new drug exposure. Drug Alcohol Depend. 2009;105(1-2):24-32. doi.org/10.1016/j.drugalcdep.2009.05.027Checked Oct 4, 2026 against the abstract.
  4. Odell MS, Frei MY, Gerostamoulos D, Chu M, Lubman DI. Residual cannabis levels in blood, urine and oral fluid following heavy cannabis use. Forensic Sci Int. 2015;249:173-180. doi.org/10.1016/j.forsciint.2015.01.026Checked Oct 4, 2026 against the abstract.