There’s been a lot of hullabaloo recently about the effects that grapefruit can have on certain meds. It has been proven that grapefruit interacts negatively with certain medications. In some instances, eating grapefruit can lower the potency of a medication, rendering it ineffective. In other cases, eating grapefruit while on certain medications can be downright dangerous, even causing sudden death.

How, you ask, can this benign and even healthful fruit have such dire effects? Grapefruit contains chemicals known as furanocoumarins that interfere with how your body breaks down drugs. They can prevent the drug from being broken down entirely. Essentially, this means that if you consume grapefruit when you’re taking a certain drug, it can be as if you’re taking five to 10 doses of that medication instead of just one, resulting in blood clots, depressed breathing, heart rhythm problems and kidney failure, just to name a few doozies. Also, as I mentioned above, the chemicals found in grapefruit can sometimes have the opposite effect on medication, breaking it down before it even reaches your bloodstream, as if you had never taken it in the first place.

So which drugs, taken with grapefruit, can form a dangerous cocktail? One you may have heard of (or even be taking) is fexofenadine, otherwise known as Allegra, a popular allergy drug. Another common one is Lipitor (atorvastatin), often taken to control high cholesterol. Lipitor is part of the statins class of drugs, a group of medications among the growing list known to become toxic when mixed with grapefruit or grapefruit juice. (By the way, this toxicity doesn’t happen only when you happen to be drinking a glass of grapefruit juice when you swallow your pills — studies have shown that having a grapefruit with breakfast in the morning can still affect the medication you’re taking before you go to bed.)

A study released late last year by the Canadian Medical Association Journal recently upped the number of drugs that interact negatively with grapefruit from 17 (the number in 2008) to 43. And the lead study author, Dr. David Bailey, says we have yet to uncover all the medications that can be dangerous.

By the way, grapefruit is not the only fruit to contain the chemicals that cause the negative interactions. Pomeloes and limes are known to have similar effects, so check with your doctor or pharmacist about those as well.

Did I scare you away from eating grapefruit entirely? I hope not. Grapefruit has lots of health benefits. It’s not only packed with vitamin C, but it also contains vitamin A, lycopene, beta-carotene and pectin, a soluble fiber that can help prevent certain cancers. Not to mention that a grapefruit at the peak of the season can be positively succulent, the perfect mix of sweet and sour flavors. (Yes, I’m writing hungry.)

Finally, grapefruit's power to boost certain medications can be beneficial, as in the case of at least one cancer drug. Researchers found that a glass of grapefruit juice so improved the body's uptake of a drug called sirolimus that the dosage could be cut by a third to reach the same effect as a full dose. This could translate into fewer side effects as well as money saved.

For a list of medications known to have interactions with grapefruit and to find out more here's the Canadian Medical Journal study. Since I don’t happen to be taking any of the meds on the list, I’m gonna go have me some ruby red.

— Chanie

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Why can't I have grapefruit while taking certain prescription drugs?
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