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.