August 2018

Statins + St. John’s wort: a big concern?

Most patients taking a statin know that grapefruit can affect how well their statin works. But they might not know that St. John's wort, a popular supplement for depression, can also affect statins. St. John’s wort can affect both the absorption and clearance of some statins.

St. John’s wort is a potent inducer of cytochrome P450 3A4 (CYP3A4) enzyme and of P-glycoprotein. CYP3A4 induction increases how quickly the liver breaks down certain statins. P-glycoprotein induction decreases how well the body absorbs certain statins. Both of these factors can decrease blood levels of statins, including simvastatin, atorvastatin (Lipitor), lovastatin (Mevacor), and rosuvastatin (Crestor). This will likely make these statins less effective, requiring a higher dose. But St. John’s wort doesn’t affect all statins. Statins that aren’t CYP3A4 or P-glycoprotein substrates, including fluvastatin and pravastatin, are unlikely to be affected by St. John’s wort.

For details about other potential statin-supplement interactions, check out our interactions checker.

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