FRIDAY, Aug. 9, 2019 (HealthDay News) -- As the CBD craze sweeps the nation, some users may wonder whether the cannabis extract can make them fail a drug test. A preliminary study suggests the answer is "no" -- at least if the CBD is pure.

Researchers found that CBD, or cannabidiol, did not react with either of two commercially available tests used to screen for marijuana use. However, another cannabis compound -- cannabinol (CBN) -- did.

CBD and CBN are two of many chemicals found in cannabis plants. They differ from THC, the source of the marijuana "high." CBD is present in marijuana but more abundant in hemp -- cannabis plants that have little THC. CBN, meanwhile, is a THC derivative.

If you think CBD products are suddenly everywhere, you're right: There has been an explosion since last year, when Congress lifted a decades-old ban on growing hemp.

Licensed farmers can now grow the plant, as long as it contains less than 0.3% THC. The result? CBD is turning up in everything from oils and lotions to coffee and cookies.

CBD is promoted for easing anxiety, insomnia and chronic pain, among other ailments. The jury is still out on those uses, but there is some science behind the compound. Last year, the U.S. Food and Drug Administration (FDA) approved a drug containing pure CBD -- called Epidiolex -- for treating certain rare, severe seizures.

CBN, meanwhile, is far less famous than its cousin, but it is used in products marketed as sleep aids.

Given that context, it's important to understand how the compounds interact with drug screening tests, said Grace Kroner, lead researcher on the new study.

She and her colleagues at the University of Utah Health Sciences Center in Salt Lake City spiked three batches of urine samples with CBD, CBN and two other cannabis compounds -- cannabichromene and cannabigerol.

The researchers tested each batch with two tests commonly used for THC screening. CBN reacted with one, while the other three compounds triggered no false-positives.

Why did only one test pick up CBN? The tests are known immunoassays -- which means they use antibodies to detect drugs. Kroner explained that there are slight differences in the antibodies that test manufacturers use -- so it's possible to get different results.