Use CBD? Here’s What to Know Before You Take a Drug Test

If CBD oil gives you relief from anxiety, pain, or other issues, you probably aren’t thinking about how it might impact an upcoming drug test. But if your employer, probation officer or someone else will be testing you for drugs, your CBD use could cause a problem. Drug tests don’t look for CBD, but depending on what you buy, your oil could come with more than just CBD.

So should you be worried about using CBD oil on the run-up to a drug test? We looked at the data and spoke to experts to find out.

Can CBD Make You Fail a Drug Test?

Yes. Although CBD itself is not covered by standard drug tests, CBD products can legally contain up to 0.3% THC, and this can make you test positive for cannabis use, or “fail”, a standardized drug screen.

We spoke to Dr. Tory Spindle, Assistant Professor at Johns Hopkins University School of Medicine and cannabis impairment testing expert, who confirmed:

“I think anyone who uses a CBD product regularly who is subjected to drug testing should be concerned about their chances of testing positive for cannabis. Even people using products that claim to be “THC-free” need to be weary, because many CBD products are inaccurately labeled and contain low levels of THC without disclosing this on the label.”

A Harvard Medical School study using full-spectrum CBD oil with 0.02% THC (Dahlgren et. al., 2021) showed that 50% of participants tested positive for THC after four weeks of use. Based on the mean of 3.5 mL of oil used per day, participants were consuming 0.8 mg of THC per day. This study used the federally-established standard 50 ng/mL cutoff for urine tests, so it is definitely possible for CBD users to fail, especially if you’re taking CBD for a prolonged period of time.

However, you won’t fail a drug test for using isolate or broad-spectrum CBD oil, as long as the product is lab-tested and doesn’t contain more THC than it claims to.

Other Research on Hemp Products and Drug Tests

• Research generally suggests (Leson et. al., 2001) that hemp-containing food isn’t a concern for drug tests, with just one participant out of 15 screening positive when consuming 0.6 mg of THC a day for 10 days. However, this participant wasn’t deemed positive by the confirmatory test (i.e. they would have “passed” a real drug test).
• A Johns Hopkins University study (Spindle et. al., 2019) tested six participants’ urine after they’d consumed CBD isolate or vaporized CBD flower containing 0.39% THC. The isolate didn’t make anybody fail the full drug test, but they did find two positive tests for the flower at the 50 ng/mL federal cutoff level for THC metabolites.

We asked Dr. Spindle, lead author of the 2019 Johns Hopkins research study, whether this result has implications for Farm Bill compliant hemp:

“I would say that our study has direct implications for people using hemp products, even though the cannabis used in our study was technically slightly over the legal limit of 0.3% THC. Our study involved 1 single use of high CBD/low THC cannabis, while most people who use CBD products do so repeatedly over weeks/months.”

Urine Tests Look for THC’s Metabolites, Not CBD

The main reason that you won’t fail a drug test because of CBD is that drug tests look for THC’s metabolites, not CBD or any of its metabolites. If you fail, it’s because you’ve intentionally or unintentionally consumed THC.

Dr. Abraham Benavides, medical cannabis coach and George Washington University School of Medicine and Health Sciences scholar, explained to us that:

“Most drug tests are federally-standardized urine drug screen (UDS) panels looking for the metabolite of THC, called THC-COOH. Our body starts to turn THC into THC-COOH as soon as it hits our liver. THC is rapidly metabolized, but the metabolite THC-COOH itself can take a very long time to finally leave the system because our body does not perceive it as harmful. It has the longest testing window of all the drugs on the panel.”

In other words, standard drug tests used for work-related screening, parole and rehabs are interested in THC, not CBD. 11-nor-delta9-tetrahydrocannabinol-9-carboxylic acid (THC-COOH) is only detected if you’ve consumed THC in some way. THC-COOH is stored in the body’s fat cells (Gonçalves et. al., 2019), and this means it can be released into the urine and detected by tests quite some time after your last use.

Other types of test are less commonly-used but still wouldn’t detect CBD use alone. Saliva testing looks for THC, blood testing can include both THC and THC-COOH, and hair testing can also include both.

How Long Is CBD Oil Detectable in Urine?

CBD itself is not part of standard drug screens, but if there is THC in the product (even in trace amounts), it could be detected for a few days after your last use and possibly longer. Unfortunately, there isn’t much evidence to answer this precisely yet.

Dr. Spindle underlined this point when we asked him this question: “This is a difficult question to give a definitive answer to and it likely will differ for everyone. It depends on a litany of factors including the dose/product they were using, their individual characteristics such as body fat, amount they exercise, among other factors.”

We also spoke to Dr. Geoffrey Smelski, PharmD, Clinical Education Director at Arizona Poison and Drug Information Center, who noted that factors such as dose and body fat percentage would be crucial to making an estimate, but added:

“For an individual patient, it would come down to whether or not they were exposing themselves to more THC daily than they were able to eliminate in a day, and thus would be “bioaccumulating” low levels of THC. In this setting, they would build up to a “steady state” or equilibrium between THC stored in adipose, what was floating around in the serum, and with how much was eliminated. This steady state amount may or may not be at levels high enough to detect on a drug test. While other users may be able to fully eliminate the amount of THC they are being exposed to, and thus almost always come up negative on a drug test (except for a period of time right after use).”

So the key issue is: what are the “steady state” levels of THC-COOH in CBD users and how do they compare to cannabis users?

The Harvard Medical School study on full spectrum CBD oil mentioned earlier (Dahlgren et. al., 2020) found that 7 of 14 participants failed a urine drug test. In this study, though, the average urine THC-COOH level was 36 ng/mL. This is not enough to actually fail the screening test (more on this in a moment), but for the time being is a good baseline for comparison.

For people purposefully and regularly smoking weed, it might take 21 days for them to pass the screening test. However, a single smoked dose of marijuana (Niedbala et. al., 2001) can easily lead to THC-COOH levels of over 100 ng/mL, and a study of chronic users (Reiter et. al., 2001) found mean levels of 260 ng/mL at first testing.

With this in mind, it’s very unlikely that the THC consumption from the trace levels in CBD oils would lead to positive results for many days after you stop consuming. It would be pretty unlucky if you even failed after 5 days of abstinence. As an estimate (based on very unclear data), 3 days of abstinence from CBD oil would likely be enough to pass the initial drug screening, provided you don’t also use marijuana itself or other THC products.

Remember: Urine Screening Tests Are Far From Perfect

In the previous section, we mentioned how the research from Harvard Medical School (Dahlgren et. al., 2020) found 7/14 screened positive for THC after taking CBD oil for four weeks, but that average levels were actually below the screening threshold. In fact, only 2 out of these 7 people should have tested positive. 

The assay used for the initial screening was advertised by CLIAwaived to conform to the federally-recommended 50 ng/mL cutoff for urine testing, but actually flagged urine samples with as little as 13 ng/mL. When the researchers performed the (more reliable) confirmatory test, only two participants actually had more than 50 ng/mL of THC-COOH in their pee. By the time you reach the confirmation test, though, the cutoff decreases to 15 ng/mL, and only one initial positive would have been overturned.

In other words, in a real-world situation, only 2 of these “should” have failed the test. But thanks to the over-senstive screening test, 6 would have actually failed the test. These people could have had their lives turned upside down, essentially because the initial test did not do what it claimed to.

Unfortunately, there may be very little you can do about this. Since the initial (inaccurate) test has to be confirmed in a more accurate way, if you meet the second test’s 15 ng/mL threshold, you’ll be deemed positive regardless of the initial test’s inaccuracy. You would be left in the same situation and ultimately dependent on people understanding and believing that CBD was the cause of the failure.

Choose the Right CBD Products (Isolate or Broad-Spectrum) to Pass Drug Tests

If you choose CBD isolate or broad-spectrum CBD products, but not full-spectrum, you’re much more likely to pass any drug test. Only full-spectrum CBD or products with lab results showing some residual THC will make you fail a test.

There are three major types of CBD extract that are used in products on the market, and making the right choice is crucial to passing any drug tests.

• CBD isolate is pure CBD, with no THC, no terpenes and no other cannabinoids. This is the best type to choose if you’re concerned about failing a drug test.
• Broad-spectrum CBD contains terpenes and other cannabinoids, but not THC. Although it’s more likely that broad-spectrum products will have traces of THC than it is for isolates.
• Full-spectrum CBD contains terpenes, other cannabinoids and THC. This was the type used for four weeks in the research mentioned above (Dahlgren et. al., 2020), which led to failed drug tests. This is because it’s supposed to contain THC; that is the point of full-spectrum products.

Any CBD product will (or at least should) tell you up-front which type of extract it uses. If you opt for broad-spectrum or especially isolate, it’s unlikely it will have enough THC to make you fail a test.

However, even if it isn’t supposed to contain THC, many CBD products still contain THC (Bonn-Miller et. al., 2017). Therefore, it’s important to check the lab results for the product you’re considering: check that any THCs (including delta-9, delta-8 and delta-10) are listed “ND” or “<LOD” (i.e. not detected or less than the limit of detection). If the product you’re considering has detectable THC or doesn’t have a lab test at all, don’t buy it.

If In Doubt, Be Up-Front About Your CBD Use

Unfortunately, even if you take the precautions above, it’s still possible you will fail the test. As Dr. Smelski commented to us, “The only way to truly prevent 100% of possible problems, would be to not use CBD.”

He suggests looking at it as a risk-benefit analysis. You may get in trouble, so does the benefit you get from CBD outweigh this risk? If you determine it’s worth the risk, he stresses the importance of being open about your use:

“I would also advise telling their employer (or whoever) about their CBD use. They could also request drug tests by their employer. They could do one prior to starting CBD and then have additional ones done after they start using it to see if anything comes back positive. If someone wanted to make an argument that their drug test was not accurate, having a clear history of proactively informing everyone of a potential false positive may go a long way. If they don’t say anything until after the false positive result comes up, that is a bit harder of an argument to make for some folks.”

Finally, though, he warns that while science is used to dealing with shades of gray, the legal system attempts to make everything black and white, so “if someone decides to use CBD and even if they do all of the proactive awareness that I suggested, a court or employer could choose to ignore all of those ’gray’ components.”

CBD Metabolites Will Be In Your System for Up to 25 Days

Although this won’t be relevant to a drug test – because they don’t look for it – CBD’s metabolites remain in your system for between 8 and 25 days following regular use.

If you’re actually interested in how long CBD use is detectable in your system, the answer can be estimated from research. Studies show (Millar et. al., 2018) that CBD has a “half life” (i.e. the time taken for half of it to be gone) of 2 to 5 days after regular oral use. It takes around 4 to 5 half lives for a drug to be essentially cleared from the system, leaving an estimate of 8 to 25 days for CBD to clear your system.  

If you’ve used CBD another way, we can estimate (from the same studies) that:

• CBD spray-like formulations will be in your system for around 2 days.
• Intravenous CBD will be present for about 5 days.
• Smoked CBD will be present for about 6.5 days.

It’s important to remember that this doesn’t mean it would be detectable by a basic screening nor that anybody would even perform one for CBD. But technically it may still be present.

Conclusion

Drug tests don’t look for CBD, but CBD often comes alongside THC, which might get picked up by a drug test. This is especially likely if you use full-spectrum CBD regularly for a long time, or if the product has more THC than the description implies. The best advice is to stick with isolate or broad-spectrum CBD, and to check the lab reports to make absolutely sure there’s no THC.