Thursday, February 7, 2013

Grapefruit: Adverse Interactions with Medication

grapefruit interactions
Many medications have adverse interactions with grapefruit
(photo from
Eat a grapefruit for breakfast. It sounds like a healthy suggestion, doesn't it? For many, the health benefits of grapefruit are obvious. Grapefruits are high in vitamin C to boost the immune system, have high levels of antioxidants to ward off cancer, contain high water levels for a flavorful hydration option, and even have fat-burning enzymes. Less obvious, however, are the potentially adverse interactions that can come from eating a grapefruit or drinking grapefruit juice while on certain medications prescribed by your doctor. 

First, realize that the reference to “certain medications” is extremely broad. The list of drugs that have dangerous grapefruit interactions is longer than most people may expect it to be. Millions of Americans are taking these common medications. That fact, along with a statistic from WebMD stating that one fifth of Americans have grapefruit for breakfast, is startling. Hopefully, the people taking those medications know about grapefruit interactions and are not part of that 20 percent.

How Does it Interact?

So what does grapefruit do that makes it react so negatively with a considerable number of drugs? According to WebMD, it interferes with how the body breaks down certain drugs due to a chemical it contains called furanocoumarin. The result is that the medication stays in your body for too short or too long, rendering it either useless or unsafely potent.

More specifically, research cited on ABC News suggests that furanocoumarins block enzymes in the intestines that break down medications in a normal metabolic process. It only takes one grapefruit or one glass of grapefruit juice to impede this important process for more than 24 hours. Because of this, taking your medications hours apart from when you normally consume grapefruit does not prevent the interaction. You may simply need to cut this acidic fruit out of your diet altogether. Fruits with similar interactions are Seville oranges, limes, and pomelos.

Ignoring this precaution about grapefruit medication interactions is not a wise idea. Drugs that note sudden death as a possible side effect could be made lethally potent from the effects of grapefruit. The chances of sudden death would be exacerbated by an interaction, basically causing an overdose of the drug. Other side effects of grapefruit interaction include heart rhythm irregularities, trouble breathing, kidney failure, blood clots, and muscle breakdown.

For quick reference, ABC News has a list of 43 specific drugs known to interact with grapefruit. Generally, WebMD lists the following types of medications as posing a possible threat when grapefruit is co-ingested:

  • Statins (cholesterol-lowering drugs)
  • Antihistamines
  • Calcium channel blockers (blood pressure drugs)
  • A variety of psychiatric drugs (including the popular Zoloft)
  • Immune suppressants
  • Pain medications (such as Methadone)
  • Impotence drugs for erectile dysfunction (such as Viagra)
  • Anti-HIV medication
  • Anti-arrhythmic medications

You may not want to limit your concern to these drugs or even this fruit, though. There are plenty of other food-drug interactions you may not be aware of. It’s important to consult a doctor or pharmacist any time you are prescribed a new medication. Don’t panic; just be sure to ask about any food-drug interactions associated with what you were prescribed. 

Above all, please don’t take these interactions lightly or ignore any warnings expressed on your prescription bottles or voiced directly to you by your doctor. Researchers feel that patients and even members of the medical community take food-drug interactions much less seriously than interactions involving medications taken with other medications. Unfortunately, both types have dangerous side effects and require some physician responsibility and consumer awareness. Improperly used, even a healthy fruit like grapefruit can cause a great deal of harm. Be informed about your prescriptions and the diet you follow while taking them. 

Amanda Gilmore
Contributing Writer

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