Grapefruit Juice and Medications

Written By: Gloria Tsang, RD

Title: Founding Registered Dietitian

Alumni: University of British Columbia

Last Updated on:

We have received e-mails from readers asking about grapefruit juice. These readers said they are confused because grapefruit, which they consider a health food, is said to be harmful when taken along with certain medications.

Yes, Grapefruit is a health food

Grapefruit is an excellent source of Vitamin C. A half grapefruit alone provides more than 75 percent daily requirement of Vitamin C! It is also a good source of lycopene, a type of antioxidant well-known for its possible anti-cancerous role. Providing a good source of fiber, grapefruit is definitely a diet-friendly citrus fruit.

Avoid Grapefruit if you are on certain medications

The exact mechanism of how grapefruit juice interacts with medications is still unknown. However, it appears that grapefruit juice dramatically increases the dosage absorbed by the body. In a study published in the American Journal of Clinical Nutrition in May 2006, researchers from the University of North Carolina identified an active ingredient in grapefruit juice called furanocoumarin. The researchers discovered that furanocoumarin interferes with drug metabolism, making our body absorb a bigger dose of the medication. This may result in drug toxicity. Check with your pharmacist about the contraindications of your medications and find out if they have interactions with grapefruit products

Not just the Juice!

The active ingredients or furanocoumarin are found not only in grapefruit juice, but also in pulps and peels. It is recommended that you avoid all grapefruit products including supplements prepared with grapefruit bioflavonoids as well as tangelo, a grapefruit/tangerine hybrid.


furanocoumarin, grapefruit


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