Grapefruit juice: Can it cause drug interactions?

I like to drink grapefruit juice. But a friend told me that grapefruit juice may interact with the medications I take. What does this mean?

- Albert / Texas

Answer

Grapefruit juice provides many nutrients, such as vitamin C and lycopene. But chemicals in grapefruit interfere with the enzymes that break down (metabolize) certain drugs in your digestive system. This can result in excessively high levels of these drugs in your blood and an increased risk of serious side effects.

The exact chemicals in grapefruit juice that cause this interaction aren't known. But these chemicals are present in the pulp and peel of grapefruit as well as in the juice. For this reason, any grapefruit product — including dietary supplements that contain grapefruit bioflavonoids — can interact with certain medications. If you avoid grapefruit, you may also want to avoid tangelos, a hybrid grapefruit, and Seville oranges, a type of bitter orange often used to make marmalade and compotes. They may have a similar effect.

If you take any of these drugs, you should completely avoid grapefruit products, tangelos and Seville oranges, unless otherwise directed by your doctor. Waiting to take these medications — even up to 24 hours — after you drink grapefruit juice will not prevent an interaction.

Talk to your doctor or pharmacist if you have concerns about the effect of grapefruit products on any of the medications you take.

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