How can grapefruit juice interact with common medications?

Dr. Michael Roizen, MD
Internal Medicine
Grapefruit juice can add to the potency (and side effects) of cholesterol-lowering statin drugs.

The good: If you drink 8 ounces of grapefruit juice a day, you may only need to take a quarter of your statin dosage.

The bad: Grapefruit juice increases the effective dose and the side effects of other drugs such as calcium channel blockers, benzodiazepines, amiodarone, and Zoloft. So if you like grapefruit juice, work with your doctor to determine the right amount of each of the pills to take.
YOU: The Owner's Manual, Updated and Expanded Edition: An Insider's Guide to the Body that Will Make You Healthier and Younger

More About this Book

YOU: The Owner's Manual, Updated and Expanded Edition: An Insider's Guide to the Body that Will Make You Healthier and Younger

Between your full-length mirror and high-school biology class, you probably think you know a lot about the human body. While it's true that we live in an age when we're as obsessed with our bodies as...

If you are taking Allegra, Lipitor, or other over-the-counter and prescription medicines, think twice before consuming these drugs along with grapefruit juice. According to Shiew Mei Huang, the acting director of the Food and Drug Administration’s (FDA) Office of Clinical Pharmacology, this fruit and drug interaction can be dangerous as grapefruit juice can affect the absorption of certain medications, and thus, the level of the drug in the blood.

In the case of the cholesterol-lowering statin drugs, such as Zocor, Pravahol, as well as Lipitor, substances in grapefruit juice block an enzyme in the gastrointestinal tract, which interferes with the drug’s metabolism, so more of the drug is absorbed in the blood. Higher blood concentrations of these drugs can cause adverse effects in the body, such as liver damage and kidney failure. Seville oranges and tangelos can also affect this enzyme.

The opposite effect can happen with fexofenadine, the drug in Allegra. Substances in the grapefruit juice block protein transporters that are needed to get this antihistamine into the body cells. Because of this, the medicine ends up being less effective in the body. Apple and orange juice can also interfere with fexofenadine so allergy sufferers should avoid these combinations, according to the FDA.

According to the FDA, grapefruit juice and grapefruits can interfere with:

• Some blood pressuring-lowering drugs, such as Nifediac and Afeditab
• Some statin drugs that lower cholesterol such as Zocor, Lipitor, and Pravachol
• Some anti-anxiety drugs, such as BuSpar
• Some anti-arrhythmia drugs, such as Cordarone and Nexterone
• Some organ transplant rejection drugs, such as Sandimmune and Neoral
• Some antihistamines, such as Allegra

Since the effects of grapefruit juice or grapefruits linger long after they are consumed, it is best to avoid these juices and whole fruit altogether when taking the above drugs. Should you currently be taking any medications, check with your pharmacist or health care provider to make sure that consuming these drugs with grapefruit juice or grapefruit will not cause an unhealthy interaction.

Continue Learning about Patient Education

Cutting Through the NSAID Confusion
Cutting Through the NSAID Confusion
News about the FDA warning that NSAIDs (nonsteroidal anti-inflammatory drugs) can be heart risky has made lots of you worried about taking those pain-...
Read More
Why don't statin drugs damage heart muscle?
Anthony L. Komaroff, MDAnthony L. Komaroff, MD
You ask an interesting question. The statin drugs that people take to lower cholesterol do somet...
More Answers
Why should I rethink taking quinine sulfate for my nighttime leg cramps?
Jill A. Grimes, MDJill A. Grimes, MD
Unfortunately, the prescription drug quinine sulfate, which has been used off-label for decades ...
More Answers
Is Sharecare About Globalized Medicine?
Is Sharecare About Globalized Medicine?

Important: This content reflects information from various individuals and organizations and may offer alternative or opposing points of view. It should not be used for medical advice, diagnosis or treatment. As always, you should consult with your healthcare provider about your specific health needs.