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Grapefruit Juice, CYP3A4 and Supplement Interactions -- glass of grapefruit juice and grapefruit halves


Yes, it's well-known that grapefruit juice can interact with many medications, including certain cholesterol-lowering statin drugs, blood pressure drugs, antihistamines, and sedatives. One of the ways grapefruit does this is by inhibiting CYP3A4, an enzyme in the liver and intestine that helps metabolize (break down) approximately 50% of all medications. This can lead to potentially excessive blood levels of these medications, increasing their effects and side effects.

Many supplements can also inhibit (and in some cases, activate) CYP3A4 and interact with many of the same medications.

Below is a list of some of the supplements known to inhibit CYP3A4. More details about each are found in our linked Product Reviews and CL Answers:

Be aware that St. John's wort can activate CYP3A4, causing a decrease in the activity of many drugs. Quercetin, echinacea, and ginseng may have similar effects.

To see a list of medications that are metabolized by CYP3A4, sign in >>

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