DATELINE: March 2000 - Adverse interactions have been reported between St John's wort (hypericum), an herbal product used to treat depression, and two drugs: indinavir, a protease inhibitor used to treat HIV and cyclosporine, a drug used to reduce the risk of organ transplant rejection. Potentially dangerous changes in drug effects can occur when medications such as cyclosporine (Neoral, Sandimmune), digoxin (Lanoxin, Lanoxicaps) and warfarin (Coumadin) are taken with hypericum extracts. Hypericum extracts can decrease the blood levels of antiretroviral medications that are used in the treatment of HIV infection, thus making these drugs less effective. Recent data show that the plasma levels of the protease inhibitor indinavir (Crixivan) were reduced by more than 50% by hypericum (St. John's wort) products. NIMH and the NCCAM are conducting a clinical trial of the safety and efficacy of St. John's wort.