People with HIV/AIDS commonly take herbals and vitamins, often without the knowledge of their doctor.

Here are examples of interactions with antiretroviral drugs that might be harmful.

Milk thistle (Silybum marianum)

  • 2 uncontrolled studies showed trends toward lower blood levels of the protease inhibitor (PI), indinavir (Crixivan) when taken with milk thistle
  • Other studies came to an opposite conclusion

St. John’s wort (Hypericum perforatum)

  • Decreases NNRTI and PIs blood levels by inducing the activity of the CYP3A4 metabolizing system
  • Interactions with indinavir and nevirapine (Viramune) are documented
  • Alternative, effective antidepressants are available, so avoid taking of St. John’s wort with antiretroviral drugs


  • Decreases saquinavir (Fortovase) absorption, perhaps due to garlic’s effect on CYP3A4 in the intestines
  • Also, two reports of people taking garlic and ritonavir who experienced gastrointestinal toxicity

Vitamin C

  • Might lower the bioavailability of indinavir


  • Goldenseal inhibits CYP3A4
  • Increased risk of toxicity from drugs that require CYP3A4 for metabolism

The bottom line?

Other herbals with even less data are included in this review. The important point is that patients should reveal their use and doctors should to discuss the benefits and risks of herbals and vitamins in the treatment regimen.

It’s surprising and disappointing that better quality studies to assess the risk/benefit for people with HIV/AIDS who take CAM are not available. This would seem to be a good area of research for a doctoral level pharmacy student.

10/1/06 13:14 JR

Hi, I’m JR

John Russo, Jr., PharmD, is president of The MedCom Resource, Inc. Previously, he was senior vice president of medical communications at, a complementary and alternative medicine website.