How long after using marijuana can a person pass a drug test?

That’s an interesting question that’s probably been asked by college athletes and employees in various sectors more times than you could count. In the United States and Canada, the most common means of testing for marijuana use is urine testing. Passing such a test is often required to remain on an athletic team or gain and keep employment.

So what’s the answer? Well, it’s a definitive “It depends.”

Urine Testing

The active ingredient in marijuana is THC. A urine test looks for the presence of THC-COOH, a metabolite of THC, and it’s produced when the liver breaks down the THC in marijuana and remains in the body for much longer.

The rate of THC metabolism varies from person to person, and it’s also affected by how much marijuana has been used. Generally speaking, a first-time user or someone who only smokes occasionally will probably deliver a positive urine test anywhere from a day to three days after use. By the end of four days, infrequent users will be below the level required to deliver a positive urine test, according to the NDCI (National Drug Court Institute).

Frequent users will likely test for about a week following their most recent use but will probably show a negative at the ten-day point. That said, there’s no guarantee that a heavy user will be free from THC metabolites within ten days – some users even test positive a month after they’ve last used. And in one (admittedly extreme) case, a user-tested positive on the 67^th day following his last use.

Is It Possible to Fool a Urine Test?

Again, athletes and employees have reason to be concerned. Marijuana is one of the most common drugs tested for, and it can get a user into just as much trouble as hard drugs when it comes to being kicked off the team or losing a job.

Drinking a lot of water to dilute the THC metabolites in the urine is the most scientifically sound solution – water dilutes EVERYTHING in the urine. But the chances of a person being able to consume enough water to achieve a negative result if they have been smoking marijuana are slim to none. Besides, diluted urine will immediately be flagged as tampered with.

As to the products available on the Internet that purport to “clean” the urine, users might just as well tear up their money and flush it down the toilet with any tainted urine they’re trying to get rid of.

And if the drug test is DOT mandated, forget it. DOT urine specimen collectors are highly trained, and they’ve completed courses that qualify them in essentially foolproof collection techniques. Substituting someone else’s urine or otherwise tampering with the specimen is simply not going to be possible. They never leave a subject alone for even a second, so substituting someone else’s urine isn’t possible.

People who don’t want to test positive for marijuana use would be well advised to leave the weed alone. The length of time that it can remain in the system is entirely too variable, and the test is reliable. The only truly reliable way to prevent a positive result is not to use it.