Just how long does THC stay in your system? This is the question in the minds of many marijuana users, particularly those who are due to undergo a drug test in the near future.
There is no disputing that THC remains in the system days after the last use of marijuana, of course, but there are a number of factors that can affect how long it does stay in the system. These include the body weight of the user, his metabolic rate, frequency of marijuana use, and the amount of marijuana typically consumed, among others.
In order to answer the question ‘how long does THC stay in your system’, it might be helpful to know more about the process by which THC is detected. The most common way to test for the presence of THC is via a urinalysis or a urine test. In the United States and many other countries, this test is often administered to potential employees applying for certain positions. Although THC is the primary active ingredient in marijuana, urine tests are actually designed to detect a substance called THC-COOH.
THC-COOH released from the liver
THC-COOH is a THC metabolite that is released by the action of the liver as it breaks down THC. Compared to THC, THC-COOH remains in the system for much longer periods of time. With most urine tests, subjects with a THC-COOH level higher than 50 ng/mL are considered ‘positive’ for marijuana use. Other tests require only 20 ng/mL of THC-COOH in the system in order to merit a positive result, while others require a result as high as 100 ng/mL.
So how long does THC stay in your system? The only reasonable answer to that question is ‘it depends’. The rate at which THC is metabolized actually varies to a considerable degree from person to person, with some people taking much longer than others to eliminate THC-COOH entirely from their systems. That being said, there are some clues as to how long the chemical remains in the body.
Occasional users – for those who smoke marijuana only occasionally, a urinalysis will likely detect THC-COOH from one to three days after last ingestion. By the end of the fourth day, infrequent users will likely register a THC-COOH level lower than 50 ng/mL. In such people, THC-COOH is unlikely to be detected three or four days after use.
Frequent users – frequent users of marijuana can expect to test positive for THC-COOH up to a week after last ingestion. With such users, 10 days should be sufficient to test negative for THC-COOH, by which time the levels of the chemical should have dropped lower than 50 ng/mL.
Heavy users – with frequent heavy use of marijuana, the period of time in which THC-COOH remains in the system is considerably longer. For such users, even 10 days would not be enough time for THC-COOH to leave the body entirely. In fact, one user who claimed to have used marijuana heavily for more than 10 years was found to have THC-COOH in his urine 67 days after last using marijuana.
The amount of time it takes for THC to leave your body depends on both your intake and your body fat ratio. Check out the useful chart below to find out roughly how long it would take for THC to completely exit your system.
Bear in mind that the figures in the table above are merely a guide. If you want to be certain that all THC has completely left your body, we highly recommend that you use a THC test. Lab Control’s Check Yourself is a test which provides an effective, yet affordable, method for checking that all THC content has left your system.
Check Yourself allows you to test yourself for four levels of THC: 20ng/ml, 50ng/ml, 100ng/ml and 200ng/ml, letting you get a close approximation of the level of THC in your body.
Using the testing kit is really straightforward. Simply dip the bottom of the device into your urine, wait five minutes, and read the result.