Does cannabis interact with other drugs?

Cannabis is a Fairly Safe Substance

Cannabis is a plant and alternative medicine that is deemed as fairly safe by most people. While some cannabis users may experience side effects, the majority of educated experts agree that it is fairly safe and cannot kill a person. They elaborate that the deaths attributed to cannabis use are likely due to other factors such as other drugs, lifestyle choices, etc. Cannabis can also be used for a wide variety of ailments like chronic pain, as an anti-nausea remedy, and a sleep aid. 

Cannabis and Other Drug Interactions Do Occur

With that being said, cannabis interacts with the same parts of our bodies that other medications do, and therefore drug interactions with other prescription medications can and do occur. It is important for medical marijuana patients to do their due diligence when it comes to their health, and consult with a physician that is educated about both cannabis and the prescription medications they are on. 

“The good news is the interaction is usually minimal and is dose-dependent,” said Dr. Jason Sims of the Higher Care Clinic. “For cannabis to interact with other medications it usually has to go through digestion (ie. Edibles). Cannabis is processed in the liver in the same place as some medications and it is there that interactions can occur. The most common interaction is that with Warfarin, an anticoagulant drug, Cannabis use with warfarin can cause an increase in a patient’s INR (International Normalized Ratio). Thus, thinning the blood, which can cause an increased risk of bleeding.”

How do cannabis drug interactions occur?

Dr. Mimi Vo of MoCannaMD said “drug interactions occur when two or more drugs react with one another due to cannabis metabolism by the Cytochrome P450 enzyme system, which also is responsible for the metabolism of several other commonly used medications. This drug-drug interaction may cause your drug to be less effective, increase the chances of unexpected side effects, or increase the actions of certain drugs. Some drug interactions can be very dangerous, for example, warfarin, a blood thinner, has been shown to increase the risk of bleeding due to increased concentration of warfarin in the bloodstream when combined with cannabis. Thus, it is very important to discuss Cannabis use with your physician as you may need monitoring of drug levels or dose adjustments of your medications.” 

A study exploring the interaction between cannabis and other drugs reads, “Drug interactions may result from chemical reactions between different components or modifications by certain components of certain biochemical pathways involved in the action or metabolism of related drugs. Drug interactions can be affected by various factors including disease and patient conditions, as well as the nature of the compounds involved.”

Specific drugs have been known to interact with cannabis

Dr. Vo acknowledged that patients need to be careful when taking the following medications and cannabis:

• Warfarin due to the increased international normalized ratio (INR) levels
• Clobazam because of the increased risk of benzodiazepine toxicity
• Central nervous system depressants like opiates because of the additive effects
• Sympathomimetics such as amphetamine or phentermine because of the additive effects
• Theophylline, clozapine, and olanzapine because it reduces the efficacy
• Anti-seizure medications such as phenytoin that reduces cannabis bioavailability 
• Verapamil, amiodarone, clopidogrel, ketoconazole, and proton pump inhibitors that increase cannabis bioavailability 

Opioids and cannabis

“A side effect of cannabis can be drowsiness or dizziness. Adding it to other central nervous system depressants, such as alcohol and opioids, can potentially cause additional worsening of drowsiness and imbalance, putting one at increased risk of falls or trauma,” Dr. Vo adds. “Cannabis increases Opioids strength, effectiveness, and how long they last in the body,” said Dr. Sims. “They do not, however, increase risk of death due to opioid overdose and actually cause a lesser dose of the opioid medication to be more effective, thereby decreasing the risk of an opioid overdose.”

CBD + THC’s interaction with other drugs 

Dr. Sims explained the difference between CBD and THC drug interactions and said that CBD alone poses less of a risk for an adverse drug interaction than THC. “It is usually the THC that interacts with other prescription drugs. CBD usually has no interactions with other prescription medications. CBD in fact has been found to decrease withdrawal symptoms in patients coming off of addictive drugs.”