How Long Does Weed Stay in Your Urine?

You’ve heard the stories: one of your friends has a urine drug test for a new job, and he hasn’t smoked cannabis in six weeks. Somehow, he fails the urine test. Another friend puffed a joint a few days ago and somehow passes the exact same urine test. So what’s the deal? How long does weed stay in your urine?

Well, the short version is, “it depends.” Think of the amount of cannabis in your system as a complex mathematical formula based on many different variables – as opposed to a simple calculation where you just measure the last time you smoked and count the number of days. The length of time that marijuana can usually be detected in urine averages out to 27 days or about four weeks, but it has been known to last for upwards of 80 days and as little as 5 or 6 days in different instances.

What Does a Drug Test Detect?

First off, let’s go into greater detail about what urine tests are specifically looking for. THC is the psychoactive compound in marijuana and one of the active agents in a cannabis plant known as a cannabinoid. However, urine tests do not search for THC. They actually detect a non-psychoactive cannabis metabolite called THC carboxylic acid, or THC-COOH. This metabolite is stored in fat cells after the body processes THC. It does not tell the drug tester whether you are high right now, but whether you have consumed cannabis in recent history.

Factors that determine how long THC-COOH will stay in your system include: how recently you’ve smoked cannabis, how frequently you smoke, your physical activities, your metabolism, eating habits, exercise habits and more. With so many different factors affecting test results, it’s difficult to pinpoint exactly how long you’ll test positive for marijuana after consumption.

For example, a one-and-done first-time user of cannabis will probably only have enough THC-COOH in their system to test positive for between 5 and 8 days. A slightly regular user (between two and four times per week) could test positive for up to three weeks after they stop smoking. An almost-every-day smoker could trigger a positive test for more than a month and up to about 50 days, while an everyday user could have high enough THC-COOH levels to fail the test two whole months after their last use.

Don’t Get Too Excited Just Yet

One thing to keep in mind is that fat cells stored with THC-COOH can introduce THC metabolites back into the body intermittently. Dehydration could result in more concentrated urine that has a higher “potency” of THC-COOH. An intense weightlifting session at the gym could cause the body to break down fat cells and release THC, resulting in a higher likelihood of a positive test if it’s done close to supplying the urine sample. Someone with a diet skewed heavily toward fatty foods will have more “storage space” for THC-COOH in their body than someone who reduces the level of sugary snacks and Quarter Pounders they eat.

It also depends on the detection sensitivity that is deemed a positive test. Some urine tests use a THC-COOH concentration of 50 nanograms per millimeter as the threshold for a positive, while others go as high as 100 ng/mL or as low as 15 ng/mL. Obviously, the higher the threshold the more leniency granted to the smoker and the window of detection for cannabis by a urine test will be shorter. In many cases, testing facilities use a two-step process: first analyzing a urine sample to see if it crosses the 50 ng/ML threshold, and if so, using a secondary 15 ng/ML threshold as the determinant of whether the test will be marked positive.

Let’s try a couple of examples. In the first scenario at the top of this article, a test comes back positive even though the subject hasn’t inhaled a toke of marijuana in six weeks. So how did this happen? Perhaps they were an everyday user, smoking of three or four grams of Ghost Train Haze per week. They have a few extra pounds of fat in their body, resulting in a greater capacity to store THC-COOH. An intense weight lifting session the day before the drug test releases THC and circulates it through the body, and they take their test when they haven’t been drinking enough water. All those factors add up to a 55 ng/mL concentration of THC-COOH and a positive test.

In the second scenario, the subject smoked some Acapulco Gold last week, the first time they had consumed cannabis in over a month. Before that, they were smoking only once or twice a week. They have a toned body and drink plenty of water every day, including several cups just before the urine test occurred. It came back at 25 ng/mL, a negative, even though they enjoyed some Mary Jane last week.

The above examples are just two of the many scenarios that could lead to different urine test results for cannabis. In reality, it’s much more complicated than the situations described above, and that’s what makes it so challenging and unpredictable. While it could take several months to eliminate all traces of cannabis use from your body, the general rule of thumb is to stop for at least a month if a urine test is impending.

The Easy Way Out

Of course, you’re asking, “But what if I am a regular smoker and I just found out that I have to pass a test next week?” Fortunately, there are some options which could help you get out of this dilemma.

There are some cleaning drinks like the Detoxify Ready Clean Tropical and the Clear Choice Rescue Cleanse that flush toxins out of the body and prevent fat cells from releasing THC back into the urine. While these are far from 100% reliable and are subject to the same variables that regularly apply, there are plenty of examples of these detox programs helping cannabis enthusiasts in a bind, and it should be considered as an option. On the bright side, the Ready Clean is packed with vitamins and herb blends, so it’s not excessively harmful to try.

Beyond the cleansing solutions, there are some basic rules that apply when trying to rid your system of cannabis traces before a drug test. The first and foremost is to consume plenty of water. Carry a bottle of water with you wherever you go, and refill it several times per day. The extra hydration will expedite the detoxification process and could be a moderate difference-maker. Some smokers will try to down a gallon of water on the day of their urine test, though this could backfire slightly because if the urine sample is too diluted, the results will be inconclusive and another test will be required.

It is also important to eat healthy foods. As previously described, eating too many processed unhealthy foods will increase the level of fat in your body, and in turn, this will allow more THC-COOH to remain stored within the fat. As an alternative, increasing consumption of green vegetables like broccoli, spinach and kale will boost metabolism and help reduce levels of THC-COOH.

It is also highly recommended to exercise heavily while in detox mode. A solid mix of cardiovascular exercise – like running and swimming, along with weight exercises like bench press and bicep curls – will burn fat and eliminate remnants of your past marijuana smoking sessions. However, it is best to avoid strenuous exercise for 24 to 48 hours before your drug test. As mentioned previously, working out can release THC metabolites from the fat cells back into the body and cause a positive test in the short term.