Every year, tens of millions of Americans undergo urine screens for marijuana. (Csaba Deli/Adobe Stock)
Tens of millions of employees in all sorts of industries are encountering new questions when it comes to drug testing in the workplace
Workers who use a lot of CBD (cannabidiol) for pain, anxiety, insomnia, or a host of other symptoms, can accidentally (and unfairly) fail drug tests for cannabis in certain cases, media and experts report.
“We are aware of a few reports of CBD users who have flunked a drug test,” said Dale Gieringer, co-director of California NORML.
In the most common workplace drug screen—a urine test—employers aren’t looking for CBD, because CBD has never been found to impair judgment or motor skills. Instead, workers fail workplace drug testing for marijuana’s main active ingredient, THC, which can exist in low amounts in some CBD products and then persist in the human body for weeks.
A CBD product’s label might misstate the amount of THC, depending on the market in which you’re shopping. State-licensed adult-use and medical cannabis stores are regulated and mandate product testing, but outside of those systems, CBD product quality can vary in a largely unregulated market. Tests of CBD products from unlicensed stores have come back positive for THC.
“It’s caveat emptor,” said Barry Sample, Ph.D., senior director of science and technology for employer solutions at the nation’s biggest drug testing company, Quest Diagnostics. “The real issue is, how do you trust the labeling?”
Furthermore, if you consume enough CBD—on the order of 1,000 milligrams a day of CBD—just the residual THC could put your test results in the danger zone. This is a big deal because a failed drug test can result in the denial of loss of both job and income, and can also lead individuals to lose access to important resources like education and welfare benefits, child custody, and prescriptions for pain medication.
Can you fail a drug test for CBD? Not really, but sort of
You won’t fail a drug test for CBD, but you could potentially fail a drug test for any residual THC in that CBD product.
Sample said Quest Diagnostics does not test for CBD. THC, however, is on the lengthy list of drugs they test for.
Here’s how drug tests work. Employers collect and send off samples—largely urine—to drug testing companies who run them through a machine that can measure trace chemicals in the liquid. Technicians look for evidence of a byproduct of THC, the main active cannabinoid in cannabis. (More rarely, employers may test saliva, hair, or blood from their employees. We’ll get to that in a minute.)
One key guideline is drug-testing rules for federal employees. A federal worker will fail a drug test if their urine tests positive for any more than a trace amount of the THC metabolite (THC-COOH). And by “trace,” we mean just 50 billionths of a gram per milliliter of urine (50 ng/ml).
THC is the most common reason a worker fails a drug test. Some 2.3% of all US drug tests came back positive for cannabis use in 2018.
Watch out for old tech
There’s also the potential that an older, not uncommon type of analytical method falsely identifies THC in a sample that only contains CBD. That method is gas-chromatography mass-spectrometry with the derivatization agent trifluoroacetic anhydride (TFAA). Tens of thousands of false positives might stem from the error annually, reporter Amanda Chicago-Lewis estimates, but at least there is some recourse—CBD users have successfully challenged a failed drug test for THC if the lab used this specific method, which can result in a false report of CBD as THC.
Why is there THC in my CBD oil?
The cannabis plant produces both THC and CBD. Medical cannabis and industrial hemp are cousins—both create dozens of similar compounds called cannabinoids.
So CBD from “federally legal” hemp can still consist of up to 0.3% THC. If you ingest very high doses of CBD—in the thousands of milligrams per day—from federally legal hemp oil, that means you may also be ingesting at least 1 mg of THC as well.
“If you’re liberal with your hemp CBD oil use, you could hypothetically test positive for THC,” said Greg Gerdeman, Ph.D., chief science officer at Colorado’s United Cannabis, makers of Prana Hemp and Prana Medicinals.
Many times, labels are just plain wrong, too. Outside of state-licensed systems, no mandatory oversight exists, said Martin Lee, co-founder and director of Project CBD.
“Mislabeled CBD products proliferate outside the licensed cannabis marketplace,” Lee said. “Some CBD products labeled as ‘THC-free’ aren’t what the label says. If a CBD user tests positive for THC, either the test is inaccurate or, more likely, the no-THC product contained some THC.”
Avoid accidental THC exposure by using state-licensed and tested CBD products. Depending on the state, CBD products can be thoroughly tested and the labels are accurate. If the label says there’s no THC in there, it’s probably true.
How much CBD will make me fail a drug test?
Again, it’s not the CBD. But flunking a THC drug test because you took CBD depends on the source of your CBD, how much you took, over how long, your metabolism, and other factors like hydration levels.
Consider your CBD oil’s source
A pure “isolate” of just the CBD molecule, which is commercially available, should not contain any THC. However, these isolates are extracted from hemp oil, and are of varying quality. By law, federally legal hemp oil can have up to 0.3% THC in it. Sometimes that number is higher, because of variations in test results.
Beyond your CBD source, dosage, length of use, personal chemistry, and other factors determine drug test success or failure.
At one end, someone who smokes high-THC cannabis every day and then stops can still fail a drug test more than a month later. That’s because the human body stores THC in fat cells and burns it into THC-COOH later, Sample said.
At the other end, you could theoretically take CBD hemp oil for months, at low amounts (50 mg/day), and never fail a urine screen for THC-COOH. It’s not clear how much CBD hemp oil is needed—or for how long—to end up with more than 50 ng/ml of THC-COOH in your urine. But certainly, if you’re taking large amounts of CBD, depending on the source, you could test positive for THC.
“Any time THC enters the body, you have the possibility of having it stored in the fat cells and slowly released,” said Sample.
How to pass a drug test for CBD
You won’t get drug tested for CBD—you’ll be drug tested for THC. If you’re concerned for any reason, you may consider following the detoxification guidelines for THC, including discontinuing use, dieting, exercise, and staying hydrated to get trace THC out of your system.
How long does CBD stay in your system?
CBD effects last 90 minutes to several hours, depending on how it is consumed. The body turns CBD into the byproduct CBD-COOH in a matter of hours, and then it sticks around for at least several days. But it doesn’t matter, because no employer is testing for CBD-COOH.
Does CBD show up on a mouth swab test?
Mouth swabs don’t check for CBD—again, they’re checking for THC, said Sample. So no, CBD won’t show up on a standard workplace drug test mouth swab. THC will, though, so keep off large amounts of CBD with trace levels of THC.
Oral fluid testing is uncommon. In 2018, general workforce testing included over 6 million urine screens, versus just 1.3 million oral fluid tests, and 200,000 hair follicle tests.
“Almost all” of those specimens are tested for THC-COOH, Dr. Sample said.
Does CBD show up in a hair follicle test?
Stop us if you’ve heard this one, but workplace hair follicle tests are generally not checking for CBD—they’re checking for that old standby THC-COOH. So no, CBD won’t show up on a standard workplace drug test of a hair follicle. THC will, though. Any CBD you took that had trace levels of THC could leave THC byproducts in a hair follicle, where they have the potential to stick around for a while. Hair follicles can contain a months-long record of drug use, depending on the length of the hair.
Can stomach acid turn CBD into THC? Unlikely
You might have read rumors online that stomach acid can turn CBD into THC. That’s possible but unlikely, according to the experts we consulted.
CBD water marketers have trumpeted this claim lately to sell CBD water over other forms of CBD, said Gerdeman at United Cannabis, which makes and sells wholesale CBD isolate.
Multiple human trials of large doses of oral CBD have never resulted in the detection of THC in the blood plasma of test subjects—so if it’s happening outside of a lab beaker, no one’s proved it. Dr. Ethan Russo debunked the stomach acid theory in Trends in Pharmacological Sciences forum article Cannabidiol Claims and Misconceptions.
At-home CBD drug testing kits
Leafly does not know of any at-home CBD drug testing kits, or why you’d take one. If you’re worried about failing a workplace drug test, you could take an at-home THC-COOH test, though accuracy varies among these products.