What are the effects of mixing cannabis with prescription drugs?

Cannabis may change how prescription drugs work and may cause possible side effects.

How drugs interact with cannabis

Drugs are metabolized and eliminated by enzymes in the liver.  The most prevalent CYP enzyme in the liver is the one responsible for metabolizing an estimated 50% of prescription medications used in clinical practice.

But, the CYP enzymes are also known to cause many clinically relevant drug-drug interactions. Some drugs induce the enzymes’ metabolic activity while others inhibit drug metabolism, which changes the concentrations of drugs present in the body as well as their pharmacokinetic profiles. For example, a drug that inhibits CYP3A4 will slow the metabolic process, resulting in an accumulation of drug concentrations and leading to an increased risk for side effects and possible drug toxicity.