#GrapefruitDrugInteractions – Beware if you are taking medications!

Screen Shot 2017-08-08 at 4.15.21 PMThe Grapefruit diet is back, again.  It’s actually been around since the 1930’s – so Hollywood, this really isn’t so new.  Many of my friend think it is a great way to lose weight & get healthy… after all, it’s just food – right?

I hate to be the boo leader (the opposite of the cheerleader – and of course, we all love cheerleaders), but those who are taking medications for cholesterol, hypertension, etc., PAY CLOSE ATTENTION.  This is our age group – so we see these interactions more frequently because those in their 20’s and 30’s aren’t on many of the typical medications we take.

Grapefruit (Citrus x paradisi)  is a great refreshing food with lots of vitamin C, Vitamin A, antioxidants, and has a tangy-sweet sour flavor, but did you know that grapefruit is believed to interact with at least 85 drugs and  that number is climbing.

What exactly does “drug interaction” mean?

According to Wikipedia’s (https://en.wikipedia.org/wiki/Drug_interaction) definition:

A drug interaction is a situation in which a substance (usually another drug) affects the activity of a drug when both are administered together. This action can be synergistic (when the drug’s effect is increased) or antagonistic (when the drug’s effect is decreased) or a new effect can be produced that neither produces on its own”.

Is it just the actual Grapefruit that can cause an interaction?

No, medications can interact with the fruit and the juice (frozen or otherwise). I know, all those wonderful salads with grapefruit, morning grapefruit, grapefruit in smoothies and of course lots of grapefruit if you are on “the diet”.

What can happen?

Drug levels may rise or fall, making them more or less potent and potentially leading to side effects (some can be quite serious).

What drugs does grapefruit interferes with?

  • Some statin cholesterol medications (atorvastatin, lovastatin, simvastatin)
  • Certain medicines that are used to stabilize heart rhythms (amiodarone, dronedarone)
  • Certain high blood pressure medications called calcium channel blockers (nifedipine, verapamil, felodipine)
  • Antihistamine called fexofenadine (Allegra)
  • Kisqali, a new breast cancer treatment approved in March 2017, states it has specific drug-food interactions with both pomegranate and grapefruit juice. They recommend that patients avoid pomegranate or grapefruit and their juices while taking Kisqali as the combination may increase the amount of Kisqali in the blood, possibly causing worsened side effects.

Types of side effects (depending on the drug and the interaction) may include:

  • abnormal heart rhythms,
  • stomach bleeding,
  • muscle breakdown and kidney damage,
  • low blood pressure,
  • difficult breathing,
  • sedation,
  • and dizziness.
  • Remember, grapefruit is also high in potassium (so if you have kidney issues, you need to be aware).

Sorry, don’t mean to scare you and not all drugs in any one class of medications may have these interactions, but you should check.  Because you are your own Health Advocate – it’s your responsibility to check and not depend on your provider or pharmacist to inform you.  You can check sites for interactions of foods and other drugs (reference below), and avail yourself of the guidance and expertise of your healthcare provider and pharmacist, just don’t assume they know everything you eat and drink.

Check over the counter medications (ex: cold, allergy drugs), or herbal supplements (ginko) you use. There may be interactions you are not aware of.  Just because they are “natural” doesn’t mean they can’t cause harm.

How much grapefruit is too much?

One whole grapefruit or 200 milliliters of juice (less than one cup) can block the CYP3A4 enzymes and lead to toxic blood levels of a drug. For example, when a common blood pressure medicine felodipine (Plendil) is taken with grapefruit juice , blood levels of the drug can triple.

If you have been warned about a possible drug interaction with grapefruit, ask your healthcare provider to describe the possible side effect and learn how to recognize it.

Discuss all of your prescription, over-the-counter (OTC), and herbal medications with your healthcare provider every time a new drug is prescribed. Better safe than sorry.

Like grapefruit, pomegranate (people use this berry and its juice for health reasons) may have an effect on how drugs are metabolized (broken down and removed from the body) due to blocking of certain CYP enzymes – like CYP3A4 and 2C9.


Cytochrome P450 enzymes are essential for the metabolism of many medications. Although this class has more than 50 enzymes, six of them metabolize 90 percent of drugs, with the two most significant enzymes being CYP3A4 and CYP2D6.  (see website below for more information)


Theoretically, drugs that may have interactions with grapefruit juice may have interactions with pomegranate juice as they affect similar enzymes. Warfarin, some blood pressure or cholesterol medications, carbamazapepine, or other drugs that are broken down by CYP3A4 or 2C9 may also have interactions with pomegranate juice. Always have your pharmacist check for drug interactions anytime you start or even stop a medication, herb, or vitamin product. Be sure to tell your doctor if you regularly drink pomegranate juice, too.



Grapefruit drug interactions




Check your drug interactions



CYP enzymes





Author: turning60andbeyond

Sandi Feaster is a registered nurse and health educator. She has worked in the corporate world as well as taken care of people with chronic health conditions. Sandi is convinced that we can improve our lives by educating ourselves and learning how we can curate the life we want. It may seem simple, but exercise and eating healthy food is the foundation of a longer, healthier and engaged life.

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