Marijuana is currently legal in 37 states making the drug more accessible than ever. Despite its legal status, most employers can still drug test current or potential employees for cannabis use if they want to. (A few states, including New York and Nevada do not allow marijuana drug testing on employees.) For individuals who use marijuana recreationally or for medical purposes, the potential of having to present an employer with a positive drug test can be anxiety-inducing. This is pretty ironic, given that weed is often used to relax!
Individuals who use CBD—which is sourced from marijuana and hemp plants but is not psychoactive the way weed is—may also wonder if a drug test would show up positive for marijuana. When it comes to how long weed and CBD stay in the body, many factors come into play including how it’s consumed and the concentration.
How Long Does Weed Stay In the Body?
“When we are talking about cannabis, the psychoactive chemical everyone is primarily concerned with is THC,” says Dr. Jenna Nikolaides, MD, an assistant professor in the department of emergency medicine at Rush University. She explains that how much THC is absorbed in the body depends on how it’s being used (for example, if it’s being smoked, vaped or consumed through food) and the type of cannabis strain.
“For example, if you are buying it in plant form, different strains have been bred to contain relatively more or less THC,” she says. “If you are buying edibles or vape liquids, these will have different THC amounts within them.”
Dr. Nikolaides says that if someone is smoking weed, THC enters the bloodstream between three and 10 minutes. “Vaping hits your bloodstream similarly fast, but the products, such as hash oils, can have an even higher potency,” she says. As far as edibles, she says it depends on the dose. “The absorption is less predictable. You'll feel it hit your bloodstream anywhere between one and six hours,” she says.
That explains how long it takes for THC to enter the bloodstream. But how long will it stay in the body? Dr. Robert Hendrickson, M.D., a professor of emergency medicine in the OHSU School of Medicine and medical director of the Oregon Poison Center at OHSU, says that while THC is only present in the body for a few hours, it can still be detected by a drug test for several days or even weeks after. He explains that this is because the THC is metabolized to a chemical called carboxy-THC. This metabolite, Dr. Hendrickson explains, lasts in the body for much longer than THC (which is what makes someone feel high).
“In general, after a single use of cannabis, carboxy-THC will be present in urine over the drug test cut off for a few days. However, if you use cannabis on a regular basis, carboxy-THC may be detectable in urine for several weeks,” he says. Dr. Hendrickson says that the reason why regular weed users have carboxy-THC detectable in their urine for longer than a one-time user is because, over time, the concentration increases which makes it detectable for longer. “There are individual factors as well,” he adds. “There is variability in how individuals metabolize THC and that might affect metabolite detection in urine. Individuals with poor kidney function may have metabolites detectable for longer.”
What About CBD?
Maybe you don’t consume marijuana, but you do use CBD. Will that show up on a drug test? It depends on how often you use CBD. “When we drug test people for cannabis, we are looking for THC and its metabolites. We don't test for CBD,” Dr. Nikolaides says. She explains that urine drug tests detect THC and carboxy-THC. However, Dr. Hendrickson says that while CBD does not have enough THC to get someone high, a regular user of CBD may accumulate enough THC so that the carboxy-THC metabolite is detectable in their urine.
Dr. Hendrickson explains that this is because hemp (the plant where CBD comes from) has a very small amount of THC. If someone consumes CBD regularly, this amount can accumulate and just might be enough to be detectable by a urine drug test.
Here’s what’s most important to keep in mind: THC from weed doesn’t stay in the body for very long—just a few hours—but its metabolite, carboxy-THC can be detected in the body for several weeks. If someone uses CBD only and not weed, it’s less likely to show up on a drug test but still possible.