Hundreds of prescriptions interact with cannabis, but drug labels won’t tell you that

Do you ever get so bored that you read the labels on your prescriptions? Yeah no, neither do we…

But if you did, you’d notice the labels have warnings about possible interactions with other drugs and products. For instance, the label on Lipitor, a drug that treats high cholesterol (and is one of the most commonly prescribed drugs in the US), warns against drinking grapefruit juice while taking it because of a potential increase in side effects.

Cannabis, which about 16% of adults in the US report using recreationally, interacts with hundreds of prescription drugs, but it’s not common to see cannabis listed on prescription drug labels. While there are some local initiatives to change that, there’s no industry-wide push to include cannabis on prescription drug label warnings.

“The responsibility for educating patients about the potential for drug interactions falls to the individuals at the point of sale, or the patient’s healthcare provider,” Leah Sera, an associate professor at the University of Maryland’s pharmacy school and codirector of the university’s medical cannabis science and therapeutics master’s program, told Healthcare Brew.

It would be no easy feat to require drug labels to warn about possible interactions with cannabis. Federal legislation is needed to do that, Sera said.

“Packaging and labeling requirements in Maryland are not the same as in New York or California or Arizona. Until we see policy changes at the federal level, it will be very hard to standardize these practices across the US,” she said.

And generally, cannabis interactions are not severe, according to Sera.

“One of the most clinically relevant drug interactions is increased sleepiness with other CNS [central nervous system] depressants such as alcohol, opioids, or benzodiazepines,” she said.

But there have been reports of an increased risk of bleeding when taking warfarin, an oral anticoagulant, and using cannabis at the same time, she added. Cannabis use could also make some drugs less effective.

“Because cannabinoids are metabolized in the liver, along with many prescription drugs, interactions may lead to increased or decreased concentrations of some prescription drugs and, consequently, an increased risk for either adverse drug reactions or decreased drug effectiveness,” Sera said.

Sera said she would like to see some labeling requirements that outline safety information, like, for example, how cannabis interacts with prescription drugs. But, she added, what’s important for cannabis users to do now is to talk “to their pharmacist or primary care physician about their personal risk for drug interactions, which is based on their medical conditions and the prescription medications they use.”