Natural Immune Booster

Potential Unsafe Drug Interactions With Echinacea

What are the potential unsafe interactions between echinacea and medications used to treat cancer, HIV, or respiratory infections?

Concerns about echinacea's potential interactions with certain pharmaceutical drugs are mostly based on evidence from lab tests:

  • Chemotherapy. Lab studies show that echinacea inhibits the enzyme CYP3A4 and it may interfere with taxane drugs (paclitaxel and docetaxel), vinca alkaloids, etoposide, and anthracyclines.(1623)
  • Hepatotoxic Medications. Theoretically may add to toxic effects in the liver, but this is disputed.(11)

Because laboratory research indicates echinacea inhibits CYP3A4, echinacea could also increase levels of the following drugs (and increase their adverse effects):(15)

Results of an animal study suggest that taking Echinacea purpurea with melatonin supplements may be harmful.(16)

Clinical Studies

There was one case reporting a possible interaction between echinacea and the chemotherapy drug etoposide. Since the lung cancer patient was also taking vitamin B12, vitamin B17, vitamin C, vitamin D, and vitamin E the doctors could not be sure effects were caused by echinacea.(16)

Despite cautions raised by lab tests, clinical studies have shown little cause for concern. Results of recent clinical studies suggest Echinacea purpurea supplements do not interfere with effectiveness of drugs metabolized by the CYP3A and CyP2D6 families of enzymes.(16)

Drugs tested included:(16)

  • Etravirine (an antiviral drug used to treat HIV).
  • Lopinavir (a protease inhibitor).
  • Fexofenadine (an antihistamine).
  • Midazolam (a drug used for sedation).
  • Ritonavir (an antiretroviral drug used to treat HIV and AIDS).

Does Echinacea Interact with Warfarin?

Echinacea doesn't appear to harmfully interfere with this common blood thinner. A randomized clinical trial on 12 healthy men determined that those who were pre-treated with echinacea followed by a single dose of warfarin did reduce blood levels of the drug. However, this did not have any significant impact on the drug's effects.(24)

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A drug used to treat anxiety disorders.(22)
Drugs used to treat high blood pressure and other cardiovascular related conditions.(22)
Drugs used to treat or prevent viral infections.(22)
Also known as laetrile, a compound found in apricot kernels.(16)
A mix of Echinacea purpurea and E. angustifolia.(16)