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Grapefruit Juice Does Not Mix Well With Some Drugs

Grapefruit juice and the actual grapefruit can be an important part of a healthy diet. Grapefruit has vitamin C and potassium — a couple of nutrients your body needs in order to work properly.

But drinking grapefruit juice or consuming a grapefruit isn’t good for you when it affects the way your medicines work.  Especially if you have high blood pressure or arrhythmia — an irregular or abnormal heart beat.grapefruit juice drug interaction

Taking Certain Medication with Grapefruit Juice

According to Shiew Mei Huang, PhD, of the U.S. Food and Drug Administration (FDA), interacting certain drugs with grapefruit juice or grapefruit can be a concern. Dr. Huang adds that the FDA has required that some over-the-counter (OTC) drugs and prescriptions taken by mouth include warnings against eating grapefruit or drinking the juice while taking the drug.

Drinking grapefruit juice can cause health problems for you when they interact with some of these drugs:

  • Drugs that treat high blood pressure, such as Procardia and Adalat CC (both nifedipine).
  • Antihistamines — like Allegra (fexofenadine).
  • Anti-anxiety drugs, such as buspirone.
  • Some drugs that treat abnormal heart rhythms, such as Pacerone and Nexterone (both amiodarone).
  • Statin drugs to lower cholesterol, such as Lipitor (atorvastatin) and Zocor (simvastatin).
  • Some corticosteroids that treat Crohn’s disease or ulcerative colitis — such as Entocort EC and Uceris (both budesonide).
  • Some organ-transplant rejection drugs, such as Sandimmune and Neoral (both cyclosporine).

Grapefruit juice does not affect every drug in the categories above. The severity of the interaction may in fact be different depending on the drug, the individual, and the amount of grapefruit juice you drink.

It’s important to talk to your physician, pharmacist or other health care provider.  Additionally, be sure to read any information provided with your prescription or OTC drug to find out the following:

  • How much, and if any, grapefruit juice you can have.
  • Determine whether your specific drug may be affected.
  • What other juices or fruits may also affect your drug in a similar way to grapefruit juice.

How Does the Juice Interfere With Medications

With most medication that interacts with grapefruit juice, “the juice lets more of the drug enter the blood,” Dr. Huang says. “When there is too much drug in the blood, you may have more side effects.”

For example, if you drink a lot of grapefruit juice while taking certain statin drugs to lower cholesterol, too much of the drug may stay in your body.  This increases your risk for liver and muscle damage that can lead to kidney failure.

Many drugs are broken down, or metabolized, with the help of a vital enzyme called CYP3A4 in the small intestine. Grapefruit juice can block the action of CYP3A4.  So instead of being metabolized, more of the drug enters the blood and stays in the body longer. This leads to too much drug in your body.

Dr. Huang says the amount of the CYP3A4 enzyme in the intestine varies from person to person. Some people have many enzymes and others may have a small amount. So grapefruit juice may affect people differently even when they take the same drug.enzyme blocked

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Although scientists have known for several decades that grapefruit juice can cause too much of certain drugs in the body, Huang says more recent studies have found that the juice has the opposite effect on a few other drugs.

“Grapefruit juice can cause less fexofenadine to enter the blood,” decreasing how well the drug works, Dr. Huang says. Fexofenadine (brand name Allegra) is available as both prescription and OTC to relieve symptoms of seasonal allergies. Fexofenadine may also not work as well if taken with orange or apple juice, so the drug label states “do not take with fruit juices.”

Find Out if You Should Avoid Juices

Ask your doctor, pharmacist or other health care provider if you can drink grapefruit juice while taking your medication.

Read the patient information sheet or the medication guide that comes with your prescription drug to find out if grapefruit juice affects your drug.  And read the Drug Facts label on your OTC drug.  The Drug Facts label should say whether you shouldn’t have grapefruit or other fruit juices with it.

If you must avoid grapefruit juice with your medicine, check the labels of fruit juices or drinks flavored with fruit juice to see whether they include this kind of juice.

Seville oranges (often used to make orange marmalade), pomelos, and tangelos (a cross between tangerines and grapefruit) may have the same effect as grapefruit juice. Do not eat those fruits if your medicine interacts with grapefruit juice.

About the author: George Zapo CPH, is certified in Public Health Promotion and Education (Kent State University). George provides informative articles promoting healthy behavior and lifestyles.

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