St. John’s wort is a yellow flowered perennial herb whose medicinal uses were first documented in ancient Greece. Some of its chemical compounds, such as the compounds hyperforin and hypericin, are thought to be the active ingredients responsible for the herb’s effects.
Initial studies suggest that St. John’s wort may work by blocking nerve cells within the brain from reabsorbing the neurotransmitter serotonin.
The effectiveness of St. John’s wort for depression has been researched in many double-blind, placebo-controlled studies. Overall research suggests that St. John’s wort for depression is more effective than placebo and about as effective as standard drugs for major depression of mild to moderate intensity.
Although scientific evidence with regards to the effectiveness of St. John’s wort for depression is not consistent, most studies have found St. John’s wort to be more effective than placebo. In addition, St. John’s wort appears to result in fewer side effects when compared to some standard antidepressants.
The results of a review of twenty nine randomized, placebo controlled trials revealed that St. John’s wort for depression was more effective than placebo and just as effective as standard antidepressants.
No less than eight studies have found that St. John’s wort for depression is as effective as standard antidepressants.
One of the studies included in an analysis of thirty seven clinical trials that decided St. John’s wort to have little benefit for major depression also found the antidepressant sertraline (Zoloft) to be ineffective. In addition, about 35% of double blind studies of standard antidepressants have likewise found them to be not much more effective than placebo.
St. John’s wort interacts adversely with many medications.