Acute mania and psychosis potentially triggered by St John's wort

St John's wort (SJW) is widely used as an herbal supplement for depressive symptoms and is generally regarded as safe. However, although extremely rare, manic and psychotic reactions have been reported, typically in individuals taking high doses, using psychotropic agents, or having a psychiatric history.

We report a case of a Japanese male in his early twenties with only one prior psychiatric visit for interpersonal stress, who developed acute manic and psychotic symptoms while taking standard doses of SJW. Shortly after returning to a university training program following COVID-19 infection, he developed emotional instability, prominent grandiose and persecutory delusions, reduced sleep, and dangerous behavior. Blood tests, cerebrospinal fluid analysis, brain imaging, and cerebrospinal fluid antibody testing were normal. Upon admission, we provisionally diagnosed him with schizoaffective disorder and initiated treatment with aripiprazole, which led to rapid improvement and near remission within 1 week. During pre-discharge psychoeducation, he reported taking SJW for several months, suggesting a possible association between SJW use and symptom onset. SJW was discontinued, and aripiprazole long-acting injectable treatment was initiated after discharge. After 2 months of sustained clinical stability, antipsychotic treatment was discontinued based on shared decision-making with the patient. Outpatient follow-up is ongoing to monitor for any recurrence of symptoms.

This case demonstrates that acute manic and psychotic symptoms may occur even in young adults with no notable psychiatric history who take standard doses of SJW. Although SJW is regarded as safe, this case highlights that severe psychiatric reactions may still arise.