Can St. John's wort trigger psychoses?

Background: St. John's wort (SJW) is a popular herbal remedy often self-prescribed for depressed mood. It has recently been associated with psychotic events. Aim: To systematically review the clinical evidence associating SJW with psychotic events. Methods: Five electronic databases were searched for all relevant reports. Data were extracted according to predefined criteria. Results: Seventeen case reports associated the use of SJW with psychotic events. In 12 instances, the diagnosis was mania or hypomania. Causality is in most cases possible. In no case was a positive rechallenge reported. Conclusion: These case reports raise the possibility that SJW may trigger episodes of mania in vulnerable patients. Clinicians should be aware of this possibility and researchers should attempt to ascertain whether the association is causal.