Don’t Mix These Meds with Grapefruit!

By Dr. Madelyn Fernstrom

Grapefruits are one of nature’s perfect fruits – low in sugar, rich in fiber, and a great source of vitamin C. But this fruit also contains a compound that can interfere with the activity of some prescription medications. A new study published this week in the Canadian Medical Association Journal reveals that the number of these drugs has significantly increased over the past few years. Researchers estimate that there are 43 drugs (26 having been introduced to the market in the past 4 years) that have been shown to cause serious harm in susceptible individuals when mixed with grapefruit.

There are three major categories of drugs that can have serious negative effects when combined with grapefruit:

- Cholesterol lowering statins

- Some heart drugs, like beta-blockers

- Some antibiotics

While food and drug interactions are printed on every label and stated on package inserts, many people do not take these warnings seriously.  The best step is to talk with your doctor, or stop in and speak with the pharmacist where you fill your prescriptions to see if grapefruit (or other foods) interact with your medication.  For some medications, grapefruit can increase the apparent dosage substantially due to grapefruit’s impact on drug metabolism. Grapefruits contain compounds called “furanocourmarins” that inhibit the normal metabolism of a medication, producing higher levels of medication in the bloodstream. 

This is of particular concern for seniors,  who generally take more medications and cannot tolerate higher dosages.

Importantly, most drugs do NOT interact with grapefruit, so it’s important to know which medications might put your at risk.  

And all citrus is not created equal when it comes to  medicine interactions. Oranges appear to have an effect, but to a much lower degree. Always check with your doctor or pharmacist for all food and drug interactions that might impact on your overall health.