What other drugs affect St. Johns Wort (Hypericum perforatum)?
St. John’s wort interferes with the way the body processes many drugs using the liver’s “cytochrome P450” enzyme system. As a result, the levels of these drugs may be increased in the blood in the short-term (causing increased effects or potentially serious adverse reactions), and/or decreased in the blood in the long-term (which can reduce the intended effects). Examples of medications that may be affected by St. John’s wort in this manner include carbamazepine, cyclosporin, irinotecan, midazolam, nifedipine, birth control pills, simvastatin, theophylline, tricyclic antidepressants, warfarin, or HIV drugs such as non-nucleoside reverse transcriptase inhibitors (NNRTIs) or protease inhibitors (PIs). The U.S. Food & Drug Administration suggests that patients with HIV/AIDS on protease inhibitors or non-nucleoside reverse transcriptase inhibitors avoid taking St. John’s wort. Case reports exist of significant reductions in cyclosporine, tacrolimus, and mycophenolic acid drug levels, and p
