Article updated: 2022 May 4. doi: 10.101511/ Author Leslie Griver, Robert Henry

Can you fail a drug test from having sex? (yes!)

Yes, you can fail a drug test after having sex for more than 1 hour.

Suppose you are a regular user of marijuana, and you need to pass a urine drug test. In that case, you’d better avoid having sex before the test.

Here’s why

Marijuana metabolites(THC and others) are stored in body fat cells. Sex can be considered an aerobic exercise.

So during the process, our body will use fat as an energy source. The breakdown of fat will release the THC into the blood, and then THC will be excreted into the urine and detected by the drug test.

But there’s a catch.

The primary source of energy for the body is carbohydrates. Carbohydrates are stored in the form of glycogen in the liver and muscles.

There’s enough glycogen in our body for about 1 hour of intense exercise.

carbohydrates fat exercise chart

So unless your sex is intense and lasts more than 1 hour, no THC will be released into the blood.

Here’s the scientific study that confirms that

The Study


Six chronic, daily cannabis users were exposed to a 45-min. moderate-intensity workout and a 24-hr period of food deprivation

Serum and urine samples were taken before and after exercises and analyzed for THC and THCCOOH by liquid chromatography-tandem mass spectrometry.

Results: There were no significant differences in the measured cannabinoid levels in serum or urine before and after physical exercise or food deprivation.

We conclude that exercise and/or food deprivation is unlikely to cause sufficient cannabinoid concentration changes to hamper correct interpretations in drug testing programs.