How long can heavy cannabis use indicate a positive result on a urine immunoassay?

Heavy cannabis use can be detected in urine for an extended period due to the way THC (the active component of cannabis) is metabolized and stored in the body. Unlike substances that are quickly eliminated, THC is lipophilic and tends to accumulate in fat tissues. When someone uses cannabis regularly and heavily, the duration of time it remains detectable in urine can extend significantly.

In the context of a urine immunoassay, heavy users may test positive for THC metabolites even after they have stopped using it. Evidence suggests that for individuals who engage in heavy or chronic use, metabolites could be present in urine for as long as one month, especially if their body fat content is relatively high, as THC is released slowly back into circulation from fat stores.

This understanding is critical for interpreting drug testing results accurately, particularly in clinical, legal, and employment settings where the timing of substance use cessation may be crucial for assessing appropriate treatment or compliance.