St. John’s Wort is often used as a herbal treatment for depression. Numerous studies report St. John’s Wort to be more effective than placebo and equally effective as tricyclic antidepressant drugs in the short-term treatment of mild-to-moderate major depression (1-3 months). It is not clear if St. John’s wort is as effective as selective serotonin reuptake inhibitor (SSRI) antidepressants such as sertraline .

Recently, controversy has been raised by two high-quality trials of St. John’s wort for major depression that did not show any benefits. However, due to problems with the designs of these studies, they cannot be considered definitive. Overall, the scientific evidence supports the effectiveness of St. John’s wort in mild-to-moderate major depression. The evidence in severe major depression remains unclear.

St. John’s wort can cause serious interactions with certain prescription drugs, herbs, or supplements. Therefore, people using any medications should consult their healthcare providers including their pharmacist prior to starting therapy.