A security officer enters the Scripps Mercy Hospital San Diego emergency entrance.
A security officer enters the Scripps Mercy Hospital San Diego emergency entrance. Photo by Chris Stone

Each time you pick up a prescription, your pharmacist might ask if you have any questions about how to take your medication or advise you about which other prescriptions might cause a dangerous interaction. Now, your local pharmacist may also caution that your medications could lead to potentially harmful reactions when combined with using marijuana.

In San Diego County, hospitals record 29 marijuana-related emergency room visits every day. Marijuana-related medical conditions include cannabis-induced psychosis, severe vomiting, cardiac and pulmonary complications, contamination, allergies, addiction and withdrawal. Additionally, marijuana and prescription drug interactions are increasing.

In response, 17 local pharmacies have come together to spread the word about the San Diego Marijuana Prevention Initiative, a program created to provide much-needed consumer information about marijuana and possible interactions with prescription medications.

Which Drugs Interact with Marijuana?

Currently very few — if any — pharmacies in San Diego provide information on drug interactions with marijuana products. But it is standard practice to include prescription label warnings about possible interactions with a number of other things. 

We are neither advocating nor discouraging the use of marijuana. However, we want the public to know that just as pairing grapefruit with statins can cause a dangerous interaction, THC and CBD — chemicals found in marijuana and cannabis products, such as gummies and other edibles — can interact with prescription medications and lead to serious side effects.

These side effects can include bleeding complications, increased drowsiness, reduced heart rate and breathing rate, extreme confusion and memory loss, poor judgement and aggression. THC, the psychoactive ingredient in cannabis, interacts with nearly 400 prescription medications, and CBD, or cannabidiol, interacts with more than 540.

Common types of drugs that can have dangerous interactions with marijuana include:

  • Sedatives — such as Ambien, Lunesta and Benadryl
  • Anti-anxiety medications — such as Xanax, Valium and Librium
  • Antidepressants — such as Zoloft, Prozac and Lexapro
  • Pain medications — such as codeine, Percocet and Vicodin
  • Anticonvulsants (seizure medications) — such as Tegretol, Topamax and Depakene
  • Anticoagulants (blood thinners) — such as Coumadin, Plavix and heparin

How the San Diego Marijuana Prevention Initiative Will Help

To ensure that San Diegans know of the dangers of marijuana use while taking prescription medications, thousands of people will receive information — in English and Spanish — about possible drug interactions. They will also be referred to drugs.com to use as a resource to check for dangerous drug interactions between THC, CBD and their own prescription medications. 

The use of marijuana can, at times, be confusing for the general public because it is legal for adults in California. And I am honored to be one of the local pharmacists to share the important message that THC can cause impairment, no matter how it is used, and marijuana can be dangerous when combined with prescribed medications. 

Next time you pick up a prescription, talk to your pharmacist about possible drug interactions between your medications and other products, food or drink items, and other medications or drugs, such as marijuana. You can also learn about possible interactions at drugs.com.

Seung Oh, PharmD, is the pharmacy supervisor at Sharp Rees-Stealy Santee Medical Center.