Grapefruit Juice:
No Appointment Necessary

Aired on Superstation WGN
Saturday, June 11 and October 15, 2005
Show 216

Dr. Lisa Thornton:

Grapefruit juice can be dangerous when it's combined with certain medications. Here's what you need to know to be safe.

Cleon Walt Stewart, PharmD, RPh:

Grapefruit juice is healthy and rich in antioxidants like lycopene. But grapefruit juice is unique among citrus fruits because it has the potential to interact with some medications. The chemicals in grapefruit interfere with some enzymes that break down certain drugs in our intestinal tract and liver, causing higher than desired blood levels of the drug and increased risk serious side effects. The exact chemical or chemicals in grapefruit that cause this interaction is unknown. But they are also present in the pulp and the peel of the grapefruit, as well as in the juice. For this reason, any grapefruit product including dietary supplements that contain grapefruit flavonoids, can cause the same interactions. Tangelos, which are a hybrid grapefruit, may have a similar effect. Some of the medications known to have potentially serious interactions with grapefruit products are anti-seizure drugs, anti-depressants, calcium channel blockers, HIV protease inhibitors, immunosuppressant drugs, and anti-arrhythmic drugs. Even waiting to take these medications up to 24 hours after you drink grapefruit juice may not prevent an interaction. If you take any of these kinds of prescriptions or if you aren't sure, avoid any grapefruit products until you've checked with your pharmacist.