In honor of 4/20 we're revisiting some of our greatest…hits.
One of the most common questions people have about cannabis is, "How long does weed stay in your system?" This is a pressing question because there are a lot of employers who require some sort of drug testing. And a failed test could seriously damage your prospects of getting or keeping a job.
The most common way that employers test for cannabis use is by analyzing urine. These tests are fairly cheap and are extremely sensitive to traces of cannabis.
So how long does marijuana stay in your system? How long can weed be detected in your urine? Read on to find out.
THC vs. THC-COOH: The Science Behind Urine Tests
The first thing you need to know is what exactly a urine test is looking for. Surprisingly, they don’t actually detect straight tetrahydrocannabinol (THC). What these tests are really trying to pick up is a chemical called THC-COOH.
When you consume cannabis, THC enters your bloodstream and gets you high. After your body processes the THC it creates a new derivative chemical. And that’s what THC-COOH is.
Urine tests have been designed to detect the presence of THC-COOH since the only way that chemical would be in your body is if you’d already used cannabis.
The problem for pot smokers is that THC-COOH stays in your system much longer than THC. That means that you can test positive for cannabis even if you haven’t smoked for days.
Time Test: How Long Does Weed Stay In My Urine?
OK, now that we’ve got a little science beneath our belts, let’s get back to the big question. How long does weed stay in your urine?
There are a few key factors that determine the answer to that question. How frequently you use marijuana, the size of your dose, and the way your body metabolizes THC all impact how long it’ll stay in your urine.
Since there are so many variables, it can be hard to pinpoint a precise amount of time that THC-COOH will stay in your urine. But researchers have come up with some general timelines that will help you gauge how long your urine will turn up positive for cannabis.
Here’s What the Research Shows
One key study found that weed can stay in a person’s urine for a surprisingly long period of time. That study found that urine will test positive for THC an average of 27 days after use. Heavy users can test positive for as long as 77 days after a smoke sesh.
One-time use will usually stay in your system for 5-8 days.
If you use cannabis 2-4 times per week and then stop, you’ll test positive for 11-18 days.
If you smoke 5-6 times per week, it’ll stay in your urine for 33-48 days.
And if you’re a serious smoker who gets high every day, weed will stay in your urine for 49-63 days.
The Problem With Urine Drug Tests
The obvious problem for anybody who uses cannabis is that you can test positive for a long time after your high has worn off. Think about it: Even if you smoke once and then stop, you can get a positive urine test a full week after you actually puffed.
Critics of drug testing have long pointed out the problem with using urine tests as a way of determining who uses drugs. These critics have pointed out that an employee who lives in a state where pot is legal can follow all the rules and still get in trouble at work when their urine test comes back positive long after they’ve actually sobered up.
Other Types Of Marijuana Tests
Although urine tests are the most common cannabis tests, there are a few others you should be aware of. Some tests look for THC in your saliva — cops use this one a lot. The good news for smokers is that THC doesn’t stay in saliva for very long. Usually, you’ll start turning up positive an hour after smoking and it’ll all be out of your saliva in 12 hours or less.
Hair follicle tests aren’t all that common because they can sometimes come back with false positives. But hair follicle tests can also be the hardest to pass. That’s because traces of cannabis can stay in your hair for anywhere from seven to 90 days.
The last, and least common, test is a blood test. Employers and law enforcement don’t use this one very often since it only detects very recent use. THC-COOH doesn’t bond well to blood cells, so it doesn’t stay in your actual blood for very long.
The Final Hit
If you have to get tested for marijuana, it’s most likely that you’ll be facing a urine test. The problem for pot smokers is that these tests come back positive long after the high has worn off and they’re fully sober.
Since it’s usually pretty hard to cheat a urine test, your best bet is to understand how long THC-COOH will be in your system by using the timelines in this article. The more you can adjust your usage for an upcoming test, the better.
In the end, though, it probably makes the most sense for heavy users to try and avoid jobs that require drug testing. And in the meantime, it’s important for the cannabis community to advocate for the elimination of marijuana drug tests since they don’t actually indicate if a person is impaired while on the job.
Even the most responsible cannabis user will still test positive for days or weeks after smoking. And when that happens they could be disciplined or cut off from a job, even if their cannabis use is legal in their state and it doesn’t affect their work performance in any way.
A version of this article originally appeared onGreen Rush Daily.
(Refinery29 in no way encourages illegal activity and would like to remind its readers that marijuana usage continues to be an offense under Federal Law, regardless of state marijuana laws. To learn more,click here .)
Like what you see? How about some more R29 goodness, right here?