St. Johns wort is a popular herb taken by many Americans. While some research suggests St. John's wort interacts with certain drugs and that it can be dangerous, none of the research has been conclusive. Investigators reviewed 22 research trials that examined drug interactions with St. John's wort. The studies included around 12 participants each. Researchers reviewed how the studies were conducted and the findings.
Researchers say three of the studies found no important interaction between St. John's wort and other drugs. However, 17 of the studies reported a decrease in blood concentration of conventional drugs when taken with St. Johh's wort.
Research shows St. John's wort has the potential to affect the way the body reacts to some drugs. However, they feel the studies are small and limited in scope. Researchers conclude that for now doctors and patients need to be aware of a possible interaction, but higher quality research is needed in the future in order to provide reliable information to the public.