Medical Research

Topicals and Prescription Medication Contraindications

Asia Mayfield
Written by Asia Mayfield

Cannabis compounds interact with your body in a myriad of ways. In addition to acting on your endocannabinoid system, these compounds can also potentially interact with any prescribed drugs that you may be taking.

Multiple studies have looked at the effect cannabis has on other medications. The studies have typically focused on the two primary cannabinoids: CBD and THC. The authors of a study published in Medicines determined that: “In general, cannabinoids are usually well tolerated, but… Caution should be undertaken to closely monitor the responses of cannabis users with certain drugs to guard their safety, especially for the elderly and people with chronic diseases or kidney and liver conditions.” (1)

Cannabis topicals represent a growing market. These creams and oils can be infused with THC, CBD, or both. There is scant research examining whether cannabis consumption methods in and of themselves affect drug interactions. However, most topicals only penetrate the first few layers of skin. The cannabinoids never reach your bloodstream, instead hitting the cannabinoid receptors in your skin.

Essentially, if THC or CBD interacts with a drug, it’s possible that the interaction may be different if you use a topical lotion than if you smoke a joint or use a vaporizer.

Dr. Greg Carter, a clinical professor of biomedical sciences at the Elson S. Floyd College of Medicine at Washington State University in Spokane, told U.S. News: “I think for any other drug that is potentially sedating or has some of the same effects as cannabis, it can enhance those effects. That’s not necessarily a drug-drug interaction in the way physicians think of it, but it can enhance the central nervous system depressing effect of other medications… So if a patient comes to me and they’re on something like Valium, I would try to get them off of Valium if I was going to recommend cannabis.”

Medications that have been shown the potential to interact with cannabis include:

  • Blood pressure medication
  • Blood thinners
  • Insulin medication

For example, THC is known to activate both your CB1 and CB2 cannabinoid receptors. When both receptors are activated simultaneously, it can trigger a cardiovascular stress response. Patients who are currently prescribed blood pressure medication need to know this before they decide to consume cannabis or use THC-infused topicals.

Cannabis is a complex plant that causes diverse reactions in the human body. When patients are considering mixing cannabis with other drugs, it’s worth their time to consider the possible interactions.


  1. Alsherbiny, M., et al. “Medicinal Cannabis—Potential Drug Interactions”. Medicines. 2019, 6(1), 3.

Image Credit: The Fix

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Asia Mayfield

Asia Mayfield

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