No, it’s realistically impossible to test positive on a marijuana drug test from taking CBD.
CBD products, including CBD-derived hemp, must be below 0.3% THC. Most CBD strains have around 8% CBD, which is considered a high-CBD strain. Some can be much higher, with a few reaching as high as 20%, and capping out at 25%, the biological limit for the cannabis genus. We will assume the worst and say hypothetical strain has 20% CBD, and is right at the 0.3% threshold. This strain would’ve been caught and turned away during laboratory testing, but we’ll assume it snuck by somehow.
Assuming the consumer used a CBD tincture, sublingual his means the average consumer only gets 20% of that 0.3% THC. 1% THC is roughly 7 mg of THC, which means that 0.3% THC is roughly 2.1 mg. 20% of 2.1 mg is 0.42 mg of THC that you possibly just inhaled. The 4% CBD translates to about 28 mg of CBD. It has a similar bioavailability and loss process as above, so you only inhale 20% of it, meaning only 5.6 mg of CBD make 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, for example, eventually becomes hydroxy-THC (11-OH-THC) which is further metabolized into carboxy-THC (11-COOH-THC). 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 0.42 mg of THC and 35% of that 5.6 mg of CBD makes it to your brain, resulting in 0.15 mg of THC and 1.96 mg of CBD making it to your brain.
Good news though, CBD has the interesting habit of lessening the psychotropic activity of THC. It inhibits the liver enzyme that breaks down THC into 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, the THC won’t even make it to the brain.
The amount of CBD you hypothetically ingested was 1219% higher than THC, or roughly 13 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 30% 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 whatever. 0.045 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 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 test is sometime after 5 days 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 0.0225 mg. It’s actually 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 0.01125 mg.
0.01125 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.
Now, quickly, we’ll redo the math with more realistic numbers and stop assuming the 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.