Anecdotal evidence has shown time and again how cannabidiol (CBD) acts as a highly effective treatment for a number of chronic, hard-to-treat ailments such as muscular pain, epilepsy, and cancer. Users of CBD strains and products are well aware that even though CBD is the second most abundant cannabinoid found in marijuana, it doesn't cause the psychoactive effects that dominate cannabis' reputation. If you use CBD-dominant cannabis strains or CBD products and are wondering if it will show up in a drug test, it's hard to offer a definitive answer.
The short answer is no, CBD will not show up in a drug test, because the most widely-used tests consist of an immunoassay with antibodies that detect metabolites produced only from the oxidation of marijuana's most famous cannabinoid, tetrahydrocannabinol (THC). These types of drug tests don't have a lot of “cross-reactivity” to non-psychoactive cannabinoids like CBD, so they usually produce negative results. However, if you consistently consume large amounts of CBD (more than 1 gram per day) your chances for this cross-reactivity to test positive increase somewhat.
Slightly more advanced than standard drug tests are Drugs of Abuse Panel tests. There are several types of these “panel” tests that aim to detect evidence of the use of a wide range of substances, including cannabis. Drugs of Abuse Panel tests actually recognize cannabinoids rather than metabolites, but they can't differentiate between THC, CBD, and the dozens of other cannabinoids found in marijuana. A gas chromatography/mass spectrometry (GC/MS) test or a liquid chromatography-tandem mass spectrometry (LC-MS/MS) test can accurately identify exactly what a substance is, including the difference between cannabinoids. These tests are expensive and usually reserved to validate or refute the results of a Drugs of Abuse Panel test and in situations when there can be no doubt about a substance's presence. That being said, if you use CBD-dominant cannabis strains that still contain some THC, these tests will show those results.
To conclude, you don't need to worry too much about a testing positive on a drug test if you're only consuming CBD strains and products that are lab-tested and don't contain THC. If you know you're taking one of the more advanced drug tests and you're acting within your state’s medical marijuana laws, it's best to have some paperwork from your doctor in hand.