East Asian herbal medicine as an adjunctive treatment for schizophrenia: a systematic review and meta-analysis

Herbal medicine is widely used as an adjunctive treatment for schizophrenia, but evidence remains limited.

To evaluate the effectiveness and safety of East Asian herbal medicine combined with antipsychotics in schizophrenia spectrum disorders.

Ten sources including MEDLINE, EMBASE and CENTRAL were searched up to January 2025 for randomised controlled trials comparing East Asian herbal medicine combined with antipsychotics versus antipsychotics alone. Primary outcome was the overall symptom scores (PANSS/BPRS). Secondary outcomes included adverse events, negative and positive symptom scores, response rates, social function, quality of life, recurrence, and adherence. Risk of bias was assessed using the Cochrane RoB 2, and evidence certainty using GRADE.

270 studies comprising 26,053 participants were included. East Asian herbal medicine combined with standard-dose antipsychotics improved overall symptom (SMD - 1.38, 95% CI - 1.60 to -1.17; 181 studies, 18,569 participants; low-certainty evidence) and reduced adverse events (RR 0.56, 95% CI 0.51-0.62; 92 studies, 8983 participants; low-certainty evidence) versus antipsychotics alone. East Asian herbal medicine combined with low-dose antipsychotics versus standard-dose antipsychotics showed symptom improvement (SMD - 0.92, 95% CI - 1.54- - 0.29; 25 studies, 1907 participants; low-certainty evidence) and fewer adverse events (RR 0.44, 95% CI 0.34-0.58; 6 studies, 450 participants; low-certainty evidence).

Low-certainty evidence suggests that East Asian herbal medicine as an adjunct to antipsychotics may improve symptoms and reduce adverse events in schizophrenia. However, most studies raised concerns regarding the risk of bias, and potential publication bias was suspected. Results require cautious interpretation and further high-quality studies are needed.