How long can drugs be detected in the body with a drug test?

Several factors influence the detection window of drugs in the body, including type of drug; frequency and dose; metabolism and body composition; the pH and concentration of the urine or oral fluid; hydration and diet; age and overall health; type of test used; preparation and route of administration to name a few. This means that detection windows can shift accordingly. Understanding these factors helps ensure accurate drug testing and interpretation of results.

General guidelines are available for detection times. Many drugs stay in the system from 2 to 4 days, although chronic use of marijuana can stay in the system for 3 to 4 weeks or even longer after the last use. Drugs with a long half-life, such as diazepam, may also stay in the system for a prolonged period of time. Drugs can be detected in hair samples up to six months, although urine and oral fluid are predominantly used for most workplace drug screening tests.

*Note: This table should be used as a general guideline only. Many variables may affect the amount of time that a drug remains detectable in the urine or other biological samples, including a drug’s half-life, the subject’s state of hydration and fluid balance, frequency of use, route of administration, cut-off concentration used by the testing lab to detect the drug, or other variables.