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Is Grapefruit Affecting Your Medications?

Grapefruit is one of nature’s many delicious treats. But could this vitamin C-rich fruit be putting you in harm’s way by dangerously interacting with your medications?

The Goodness in Grapefruit

Image for grapefruit article Grapefruits are low in calories and packed with benefits. One cup of fresh grapefruit gives you a huge serving of vitamin C (79 mg), not too mention other important nutrients like vitamin A, folate, beta carotene, and lycopene.

With all of these excellent qualities in one fruit, it is hard to imagine that it can cause harm. But having a diet that includes grapefruit and taking certain medications can negatively impact your health.

How the Grapefruit/Drug Interaction Works

Cytochrome P-450 is a group of enzymes located throughout the body, with the largest amount found in the liver and the intestinal walls. This family of enzymes is responsible for making chemical reactions needed to breakdown many different compounds, from food to drugs. CYP3A4 is the most abundant member of the enzyme family. It is responsible for breaking down approximately 60% of the drugs we take.

When grapefruit or grapefruit juice is consumed, a compound within the grapefruit disrupts the CYP3A4 enzyme’s ability to metabolize a drug. If a drug is not adequately metabolized, higher levels of the drug may enter the bloodstream, which can lead to a potentially dangerous situation. These interactions have been observed within a few hours after consuming grapefruit and may last for up to 3 days. As little as 8 ounces (237 milliliters) can have an effect on the metabolism of some drugs. Some other citrus fruits, such as pomelos and Seville oranges (a bitter orange used in marmalades and compotes) can have similar effects.

Which Drugs Are Affected?

Below are examples of medications that can be affected by grapefruit.

Give Up Grapefruit?

In light of this interaction information, would it be safer to avoid grapefruit? Although a possible drug interaction is a serious matter, giving up grapefruit may not be necessary. If you are taking any medications and you enjoy eating grapefruit or drinking grapefruit juice, it is important that you talk with your doctor. Ask specifically about the possibility of interactions with any prescription or over-the-counter drug that you are taking. Your doctor may be able to prescribe a medication that won't interact with grapefruit juice.

  • Family Doctor—American Academy of Family Physicians

  • US Food and Drug Administration

  • Canadian Pharmacists Association

  • Health Canada

  • American Academy of Family Physicians. Medicine interactions with grapefruit: what you should know. Am Fam Physician. 2006;74(4):611. Available at: Accessed February 4, 2016.

  • Grapefruit/grapefruit juce drug interaction information for health professionals. University of Florida College of Pharmacy Center for Drug Interaction Research and Education website. Available at: Accessed February 4, 2016.

  • Grapefruit, raw, pink and red and white, all areas. USDA National Nutrient Database for Standard Reference website. Available at: Accessed February 4, 2016.

  • Stump AL, Mayo T, et al. Management of grapefruit-drug interactions. Am Fam Physician. 2006;74(4):605-608.

  • Verapamil. EBSCO DynaMed website. Available at: Updated January 25, 2016. Accessed February 4, 2016.