When a parent suspects their child may be using marijuana, the natural response is to consider at home drug testing, but it is important to first learn how long marijuana stays in the system. On average, trace amounts of THC, which is the psychoactive ingredient in marijuana, can be detected for 4 weeks after the drug was last ingested. There are, however, crucial variables to consider when determining how long marijuana stays in the system, such as length of use, the potency of the marijuana, and the use of natural remedies to conceal the presence of drugs. Without this critical knowledge, testing for past or present marijuana use may prove difficult because the drug can be detected differently under various circumstances. For example, with chronic users of marijuana who smoke the substance regularly, marijuana stays in the system for a much longer period of time after the last instance of use. On the other hand, for someone who has only tried the drug once or twice, marijuana stays in the system for just 3-4 days.

The question of how long marijuana stays in the system is also dependent on which option you choose to utilize. A standard urinalysis drug test can detect traces of THC in the body for 2-4 weeks after use. The hair follicle drug test has a much wider range of detection, and is able to confirm marijuana usage up to 1 year after the last ingestion. Because THC is stored in fat cells, which are present in the bloodstream, blood testing for marijuana use is considered to be highly accurate in determining how long marijuana has been in the system. Gaining a clear picture of the subject’s drug use, from the first time smoker to a habitual marijuana addict, will help you assess exactly which home drug testing option is the best for your situation. Determining how long marijuana stays in the system is the first step towards implementing a strong, effective, and accurate home drug testing program.