A British researcher reports that data leave little doubt that St John's wort interacts with the immunosuppressive drug cyclosporine, causing a decrease of cyclosporine blood levels and leading in several cases to transplant rejection.

Dr. Edzard Ernst of the University of Exeter expressed concern in the Archives of Surgery that healthcare professionals are often unaware that their patients are taking St. John's wort, a popular herbal supplement widely promoted as a natural antidepressant.

Ernst said he had identified reports of 86 transplant patients whose blood levels of cyclosporine -- a drug many take to prevent rejection of their transplanted organ -- dropped 30 percent to 75 percent when they began taking the herbal remedy.

"The public continues to believe that herbal medicines are safe, and the media contributes to perpetuating this myth. The truth is, however, that numerous herb-drug interactions must be considered," Ernst said.

"St John's wort can endanger the success of organ transplantations," Ernst concluded. "Adequate information may be the best way to avoid future incidences."

Other sources: Archives of Surgery