Yes, you may fail a drug test even if you experience no mood-altering affects from your CBD-rich medicine. Drug tests are geared toward identifying THC, not CBD or another cannabinoid. Medicating with CBD-rich cannabis that has a small amount of THC, the THC may register on the drug test.
CBD is metabolized into an analogous compound, 7-hydroxy-CBD, by the liver. Some 6-OH-CBD may also be formed. But scientists know relatively little about the activity (or lack thereof) of these compounds. There is strong evidence that CBD does not convert to significant amounts of THC in the stomach.
Yes. CBD inhibits the cytochrome P450 enzyme, which is involved in metabolizing many drugs. Compounds in grapefruit inhibit the same enzyme group, which is why physicians advice patients not to eat grapefruit shortly before or after taking a medication. By inhibiting cytochrome P450, CBD can either reduce or increase the effects of other drugs. In some situations, it may be advisable for a physician to monitor a patient’s blood levels of other medications while taking CBD.