Guides
How long does THC stay in urine?
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.
How long does THC stay in saliva?
A mouth swab (oral fluid) test looks for THC itself. Above the federal 2 ng/mL confirmation cutoff, a NIH study found THC for up to about 32 hours in occasional users and 72 hours in frequent users, the last time point it sampled.
How long does THC stay in hair?
A hair test can reflect roughly the last 3 months of use, about 1 cm of hair per month. It finds heavy, near-daily use far more often than light use: in one study, 77% of heavy users and 39% of light users tested positive for THC.
How long does THC stay in your blood?
Blood tests measure THC itself. After one cannabis cigarette, occasional smokers fell below 5 ng/mL within about 2 hours. In some daily users, studies found THC in blood for 7 days or more, and in a few for up to 30 days.
THC drug test meaning: what a result actually says
A THC drug test reports whether a sample is above a set cutoff, not how much someone used or when. Federal urine rules screen at 50 ng/mL and confirm at 15 ng/mL of THC-COOH; oral fluid rules use 4 and 2 ng/mL of THC.
Sources and method
Every figure on this site comes from a federal testing rule, a federal statute or a peer-reviewed study. Each carries the number of its source, and the list says what part of the source was read and when.
Does delta-8 THC show up on a drug test?
Often, yes. In a 2023 lab study, six common urine cannabinoid screening kits reacted to delta-8 THC and its metabolites, at levels that varied by kit and cutoff. A delta-8 product can also contain delta-9 THC.
CBD flower, hemp flower and drug tests
Drug tests look for THC and its metabolite, not CBD. But hemp flower may hold up to 0.3% delta-9 THC, and high-THCA hemp flower produces THC when smoked, so either can lead to a positive THC test.