St. John's Wort is a natural health product promoted as a treatment for mild depression or as a sedative.
Drug interaction can seriously alter or diminish the effectiveness of the prescription medication.
A recent clinical trial, published in the medical publication Lancet, showed that St. John's Wort, when administered in conjunction with indinavir, a protease inhibitor used to treat HIV infection, significantly decreased the protease inhibitor's presence in the blood stream. With such a decrease, the drug becomes considerably less effective and may promote the development of viral resistance to the drug. Because some other AIDS drugs are metabolized in a similar way to indinavir, the possibility of interactions with these drugs should also be considered. Therefore, those patients currently using St. John's Wort concurrently with any antiretroviral drug are strongly urged to consult their health care practitioner. In certain cases, use of St. John's Wort by transplant patients has been associated with acute organ transplant rejection in conjunction with a decrease in cyclosporine values in the blood stream below the therapeutic range.