February 9, 2016

Grapefruit Can Interfere with Prescription Medications

First, here is some positive information about grapefruit. It’s delicious when broiled with a bit of brown sugar. It’s packed with vitamin C, dietary fiber, and potassium. It’s good for the immune system, skeletal system, and the cardiovascular system!

Yes, grapefruit has some good points and is generally healthy for you. However, grapefruit has a bad side and many people fall victim to the worse side of grapefruit. Grapefruit has earned the ire of some for its potential to cause harmful drug interactions and is known as the grapefruit effect. But, why is it specifically grapefruit and grapefruit juice that’s singled out?

Even though the harmful drug interactions have been known for several decades, many doctors still do not warn patients when they prescribe a drug known to be on the list. To begin with, the chemical in grapefruit that we’re going to talk about is called furanocoumarin. It’s a toxic chemical found in many plants that functions as a line of defense against would be eaters through a bitter flavor and by causing potential stomach issues.

It’s that exact line of defense that causes the drug interaction. Furanocoumarin is also found in most other citrus; but sour oranges, some mandarins, and tangelos have higher concentrations, though not as high as grapefruit.

The chemical doesn’t interact directly with medications, but instead binds itself to an enzyme found in the liver and intestinal tract. The enzyme in question is known as CYP3A4. This enzyme helps regulate how much of a drug may enter your bloodstream.

Essentially, furanocoumarin puts CYP3A4 into a headlock; as a result, it can’t do its job, so a medication seeps into your bloodstream at an increased rate. Certain drugs show different effects. Men taking Viagra may see the drug hit harder and faster, which may sound good but likely, this may come along with headaches, dizziness or even vomiting. None of which will help sexify the mood.

The FDA notes that cholesterol lowering drugs known as statins often have harmful interactions with grapefruit juice. These can include dizziness, harm to the liver and kidneys, and muscle breakdown. In one Mayo Clinic study, some people even showed signs of memory loss.

Some psychiatric and anxiety medications have also displayed signs of the grapefruit effect, including upset stomach, digestive issues, and exhaustion.

If you’re unsure of what drugs interact with grapefruit juice you can see a partial list here. I have more in this blog and this blog.

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