All CBD products regulated in the US must have a THC percentage below 0.3%, with anything testing above being considered a THC product. The same rule applies to hemp-derived CBD; not only do the extracted products have to be below 0.3% THC, but the hemp plant itself must have less than 0.3% THC production in its resin glands, called trichomes.
CBD in Testing
Even with the 0.3% THC limit, consuming any form of CBD will never produce enough THC in the body to be properly metabolized and bound to fat, which would increase the risk of a positive marijuana drug test. Positive results from CBD products are conclusively the result of mislabeled or improperly made CBD products, and are a lesson in ensuring the products you’re taking are reliable and contain the ingredients they claim.
If you’re smoking CBD-rich hemp, vaping CBD oil, dabbing CBD wax, using a CBD topical, or ingesting a CBD tincture, edible or capsule, you will never test positive on a marijuana drug test as long as the CBD product you’re using is truly below 0.3% THC. I’ll be primarily focusing on CBD-rich hemp as I do the math below, but the same general processes are involved in vaping and dabbing CBD as well. Topical applications of CBD, or even THC, never enter the bloodstream as long as they’re not applied to open wounds, so there’s no risk of testing positive on those either.
One of the earliest National Institute on Drug Abuse (NIDA) studies on cannabis smoking conducted in 1982 by researcher Richard L. Hawks, as well as a later study done in 1990 by Mario Perez-Reyes, a psychiatric researcher at the University of North Carolina, estimated that 20% – 37% of THC hits the consumer in mainstream smoke, 23% – 30% is lost to pyrolytic destruction and 40% – 50% goes up in sidestream smoke. In these studies, the concern was THC, and other chemicals such as CBD and terpenes, weren’t widely known. All of these studies utilized low-quality, low-potency cannabis supplied by NIDA, testing at around 1.5% – 3% THC content. The THC average these days is closer to 20%.
We’ll assume a best case scenario for the THC binding, so a worst case scenario for the consumer testing positive. The average CBD-rich hemp variety these days is at around 15%, but we’ll be generous and assume that this particular strain is at the absolute limit that the cannabis plant is biologically able to produce; 25% CBD. In a perfect world, this would mean you’d get 175 mg of CBD out of this strain of hemp if you smoked all of it, but as explained above, quite a lot is lost to combustion and smoke when inhaled. Since only 37% of that CBD will reach the consumer, assuming it’s incredibly efficient, only about 65 mg of CBD is actually inhaled.
Since we’re worried about the amount of THC you’re inhaling, we need to remember that only 0.3% of that 175 mg CBD is THC, which means the entire amount of bud has only about 0.5 mg of THC. You will only properly inhale 37% of that, assuming once again the worst case scenario, meaning about 0.195 mg of THC makes it to your lungs.
Next, the THC is transported through the bloodstream from your lungs to your liver. Here, the enzymes break the phytocannabinoid down into further metabolites; THC eventually becomes 11-hydroxy-THC (11-OH-THC) which is further metabolized into 11-nor-9-carboxy-THC (THC-COOH). These metabolites are what’s being tested for in marijuana drug tests, so it’s important to know just how many will be produced from the 0.2 mg of THC you just inhaled. The bioavailability of phytocannabinoids such as THC have a variance between 10 – 35% when inhaled, a very high number, meaning two users can take an equal dose, and one of them could possibly experience a 3x higher THC concentration. We’ll assume you have the higher bioavailability, and 35% of that 0.195 mg of THC makes it to your brain, resulting in 0.068 mg of THC making it to your brain.
Good news though, CBD has the interesting habit of lessening THC’s ability to bind properly. It inhibits the liver enzyme that breaks down THC into 11-hydroxy-THC (11-OH-THC). It does this by binding to the enzyme itself before THC has the ability to, changing the shape of the enzyme until the CBD has been broken down fully. It’s actually so effective at doing this, that if the CBD ingested is greater than 4 times the amount of THC, which should always be the case in all CBD products, THC’s ability to be processed is extremely hindered within the body.
The amount of CBD you hypothetically ingested was 34,900% higher than THC, or roughly 350 times more. This is a major hindrance on even THC’s ability to be metabolized and stored in fat. Let’s assume the worst yet again, and say that a solid 10% of the THC still makes it through to be metabolized and stored in fat. This is quite literally impossible in a normal functioning body, but we’re once again assuming the absolute worse. 0.007 mg of THC is stored.
THC concentration moves to numerous places throughout the body after consuming cannabis. It can be detected in the blood, urine, feces, brain, high perfusion tissues, low perfusion tissues and fat. 48 hours after consuming cannabis, most of the THC has been moved away from the blood, brain and high perfusion tissues, but are increasing in concentration in low perfusion tissues and fat. Around 50 – 90% of THC and other phytocannabinoids are excreted from your body in the first 4 or 5 days. 80% of this excretion is via feces, with only trace amounts in the urine. Urinalysis is still used for testing simply because laboratory personnel don’t like handling feces. Phytocannabinoid fat content in fat continues to heighten, and only begins to subside slowly after roughly 10 days, but can remain in trace amounts for up to 90 days, notably in hair follicles.
Let’s assume your drug test is 5 days after the last time you took the CBD oil. We’ll continue to assume the worst, and say only 50% of that THC makes it out, dropping it down to 0.003 mg. It’s fairly evenly distributed among fat molecules as it’s transported around the bloodstream, but we’ll again assume the worst, and that the majority is bound to your hair. That’s another 50% in hair (10% in blood, 10% in urine, 10% in feces and 20% in tissues, very unrealistic), dropping it down to 0.0017 mg.
0.0017 mg of THC is what ends up being bound to your hair follicles, assuming the worst at practically every possible situation. That’s negligible. It’s such a small amount that they’d need fistfuls of hair, multiple tests and a perfect lab experience every time to get a positive, and even then I’d say it’s impossible. The numbers just don’t support it.
With a more realistic outlook on all the previous numbers, the hemp was likely closer to 8% CBD with a maximum amount of 0.1% THC. That 0.1% would be around 0.7 mg of THC, only 20% of that makes it to the lungs, becoming 0.14 mg of THC entering your body. Liver efficiency is likely closer to 17%, meaning only 0.02 mg of THC metabolites make it into the body. Possibly just 1% of those metabolites aren’t hindered by CBD, meaning roughly 0.0002 mg of THC make it to their binding sites. Roughly 20% of that will be bound to hair follicles, resulting in about 0.00004 mg of THC having the ability to show positive on a drug test. Realistically, it is not possible to test positive on a marijuana drug test from ingesting CBD in this way.
Now, quickly, we’ll redo the math with more realistic numbers and stop assuming a worst case scenario. Your strain probably had 8% CBD and a max of 0.1% THC. 8% CBD translates to about 56 mg of CBD. 0.1% THC translates to about 0.7 mg of THC. 20% of 56 mg of CBD properly makes it to the lungs and into the bloodstream, resulting in 11.2 mg of CBD. 20% of 0.7 mg of THC properly makes it to the lungs and into the bloodstream, resulting in 0.14 mg of THC. 17% of 11.2 mg of CBD is broken down by the liver and passed along, resulting in 1.9 mg of CBD. 17% of 0.14 mg of THC is broken down by the liver and passed along, resulting in 0.02 mg of THC. 1% of 0.02 mg of THC is broken down properly and not hindered by CBD, resulting in 0.0002 mg of THC. 80% of 0.0002 mg of THC is bound to other places, and only 20% is bound to hair follicles.
0.00004 mg of THC is bound to your hair. You will never test positive.