Read on to learn more about how long marijuana can be detected in urine, blood, saliva and hair. When you use marijuana, your liver breaks it down into metabolites. Approximately 20% of the metabolites leave the body through the urine, while the remaining 80% are eliminated in the form of faeces. A urine drug test looks for metabolites in the urine.
On average, urinalysis can detect THC for three to seven days. That range will depend on how much marijuana you use and for how long. Tests can detect THC in urine for up to 30 days in a heavy user who uses marijuana at least once a day for up to 30 days.