Serious psychiatric and neurological adverse effects of herbal medicines -- a systematic review

OBJECTIVE: Psychiatric and neurological patients frequently try herbal medicines often under the assumption that they are safe. The aim of this systematic review was to provide a summary of recent data on severe psychiatric and neurological adverse effects of herbal remedies. METHOD: Computerized literature searches were carried out to identify all reports of psychiatric and neurological adverse effects associated with herbal medicines. These data were subsequently extracted, validated and summarized in narrative and tabular form. RESULTS: Numerous case reports comprise a diverse array of adverse events including cerebral arteritis, cerebral oedema, delirium, coma, confusion, encephalopathy, hallucinations, intracerebral haemorrhage, and other types of cerebrovascular accidents, movement disorders, mood disturbances, muscle weakness, paresthesiae and seizures. Several fatalities are on record. They are caused by improper use, toxicity of herbal ingredients, contamination and adulteration of preparations and herb/drug interactions. CONCLUSION: Herbal medicines can cause serious psychiatric and neurological adverse effects.