advertisement



Q & A Library


Print this page | Sign up for free e-bulletins
 | Bookmark This Page

Q
No More Grapefruit Juice?

I understand that many more drugs than previously thought can have unintended effects if you take them after drinking grapefruit juice. Can you tell me which drugs are affected and whether it is important to avoid grapefruit juice altogether or just not use it to wash down pills? 

A
Answer (Published 1/24/2013)

Grapefruit juice contains substances that can influence the absorption and metabolism of a number of drugs. If you drink grapefruit juice and take prescribed medications, the effects of the drugs can be multiplied. In some cases, this can lead to serious medical problems such as kidney damage, gastrointestinal bleeding, bone marrow suppression in immunocompromised patients, respiratory failure, and even death. In other cases, drug effects can be reduced so you’re not getting as much of medication as you should.

Related Weil Products
Dr. Weil's Vitamin Advisor for Your Whole Body - Foods, herbs and drugs can all interact, sometimes in unexpected ways. Dr. Weil's Vitamin Advisor takes known interactions into account when developing nutritional supplement recommendations, to help safeguard against adverse effects. Learn more, and get your free, personalized Dr. Weil's Vitamin Advisor recommendation today.

The compounds believed responsible for the grapefruit juice effect on drugs are called furanocoumarins. They block an intestinal enzyme, CYP3A, from partially metabolizing and eliminating certain drugs as they are absorbed. For example, after only three days, the concentration of a statin drug used to reduce cholesterol was 330 percent higher than it should have been when it was taken with a daily glass of grapefruit juice instead of with water.

We’ve known about the grapefruit effect for more than 20 years, but in an article published online on November 26, 2012 in the Canadian Medical Association Journal the researchers who originally characterized the grapefruit effect reported that the number of prescription drugs now known to be affected by grapefruit juice is on the upswing. Between 2008 and 2012, that number had jumped from 17 to 43. This is an average rate of increase of more than six drugs per year, according to the article.

Originally, the drugs in question included calcium channel blockers used to treat high blood pressure, non-sedating antihistamines such as Hismanal (astemizole), certain tranquilizers including Valium (diazepam), Xanax (alprazolam), Halcion (triazolam), and others, a number of cholesterol-lowering drugs, including Lipitor (atorvastatin), Mevacor (lovastatin) and other statins, and the immunosuppressive drugs used to prevent rejection of transplanted tissues organs and the antiviral agents used to treat HIV/AIDS. Now the list also includes anticancer agents, anti-infective agents, cardiovascular drugs, gastrointestinal drugs, urinary tract agents and drugs affecting the central nervous system.

If you take any of those drugs with grapefruit juice, you may feel a difference. With calcium channel blockers you might notice flushing, headache, an increased heart rate, or blood pressure that is lower than intended. With the tranquilizers, you may notice increased sedation. Grapefruit juice can even enhance your response to caffeine, resulting in nervousness and over-stimulation.

Other citrus fruits such as Seville (bitter) oranges used in marmalade, limes and pomelos also contain the furanocoumarins capable of inhibiting the CYP3A4 enzyme. This reaction can occur even if you drink grapefruit juice or consume marmalade, limes or pomelos many hours before taking your pills.

The good news is that you can find out whether a drug you may be taking interacts adversely to grapefruit juice (or grapefruit itself) by reading the package insert included with your medication. Or, you can ask your pharmacist when you pick up your prescription.

Andrew Weil, M.D.

Creative Commons License Some Rights Reserved Creative Commons Copyright Notice
A portion of the original material created by Weil Lifestyle, LLC on DrWeil.com (specifically, all question and answer-type articles in the Dr. Weil Q&A Library) is licensed under a Creative Commons Attribution-Noncommercial-No Derivative Works 3.0 United States License.

The Weil Vitamin Advisor
Get your FREE personalized vitamin recommendation & supplement plan today!

Dr. Weil on Healthy Aging
Your Online Guide to the Anti-Inflammatory Diet. Start eating for your health - begin your free trial now.

Dr. Weil's Spontaneous Happiness
Achieve emotional well-being
in just eight weeks!
Start your 10-day free trial now!

Vitamin Library
Supplement your knowledge with Dr. Weil's essential vitamin facts. Learn why they are necessary and more.

Dr. Weil's Optimum Health Plan
Your 8-week plan to wellness.
Begin your journey today!
 

Dr. Weil's Head-to-Toe
Wellness Guide

Your guide to natural health.
Use the Wellness Guide today!

Dr. Weil's Anti-Inflammatory Diet Food Pyramid
Our interactive tool can help improve overall health through diet.

Condition Care Guide
Learn about health conditions from acne to vertigo, and Dr. Weil's view of the best treatment options for each.

Healthy Recipes
Discover a treasure trove of healthy, healing foods and creative, delicious ways to prepare them.

Q&A Library
Over 2,000 questions from you
and their corresponding answers
from Dr. Weil.

 
Copyright © 2014 Weil Lifestyle, LLC
Information on this web site is provided for informational purposes only and is not intended as a substitute for the advice provided by your physician or other healthcare professional. You should not use the information on this web site for diagnosing or treating a health problem or disease, or prescribing any medication or other treatment.

Ad Choice
Advertising Notice

This Site and third parties who place advertisements on this Site may collect and use information about your visits to this Site and other websites in order to provide advertisements about goods and services of interest to you. If you would like to obtain more information about these advertising practices and to make choices about online behavioral advertising, please click here