Five things to know about drug interactions with cannabinoids

Reviewed by James Ives, M.Psych. (Editor)Mar 2 2020

A practice article provides 5 things to know on how drugs can interact with cannabinoids in CMAJ (Canadian Medical Association Journal).

1. The antifungal drug ketoconazole was shown to nearly double cannabinoid levels. Similar effects might be seen with commonly used drugs, such as macrolide antibiotics, increasing the chance of cannabinoid-related adverse effects.

2. Cannabinoids can affect levels of other drugs, increasing levels and the risk of adverse effects.

3. Smoking marijuana regularly can increase clearance of some drugs.

4. Marijuana can have additive effects with certain drugs, and may cause tachycardia (rapid heartbeat), high blood pressure and depression of the central nervous system.

5. Although more research is needed, potentially serious interactions with marijuana can occur with the blood thinner warfarin and specific drugs used for asthma and seizure control.

Patients and physicians should be aware of these potential interactions and effects.