01
Why THC stays so long
THC is fat-soluble, which means it binds to fat cells rather than washing out with water like alcohol. Those fat cells slowly release THC metabolites (mainly THC-COOH) over days and weeks. Heavy users accumulate more THC in fat stores, which extends detection windows. Body fat percentage, metabolism, and recent exercise all affect clearance.
02
Urine testing, the most common
Occasional users (once a week or less): 3 to 7 days detection. Regular users (3 to 4 times a week): 10 to 15 days. Daily users: 15 to 30 days. Heavy daily users (multiple times a day, concentrates): 30 to 60+ days. The test looks for THC-COOH, the metabolite, not THC itself. Standard cutoff is 50 ng/mL.
03
Saliva testing, short window
Detects recent use, typically 1 to 3 days after last consumption. Commonly used for roadside testing in some states. Saliva tests are the least predictive of impairment but the easiest to administer on-site. Heavy users may test positive longer than 3 days, but not by much.
04
Blood testing, actually predicts impairment best
Detects active THC for 2 to 4 hours in occasional users, up to 7 days in heavy users. Blood is the only test that actually correlates with impairment in most cases. Used in DUI investigations and some medical settings. THC levels drop quickly after consumption, which is why blood tests have narrower windows than urine.
05
Hair testing, longest window
Hair follicles incorporate THC metabolites during growth, creating a timeline of use that lasts up to 90 days depending on hair length. Used in some pre-employment screenings and custody cases. Hair tests can miss very recent use (last 7 to 10 days) because it takes time for the metabolites to reach visible hair shaft.
06
Can you speed up clearance?
Not meaningfully. Hydration, exercise, and healthy diet support normal metabolism but won't dramatically shorten detection windows. 'Detox drinks' temporarily dilute urine but don't actually flush THC faster, labs usually catch the dilution. The only reliable clearance is time and abstinence.