Malignant syndrome is not a disease, but a rare and serious adverse reaction. Patients present with fluctuations in consciousness, muscle tonicity, hyperthermia and autonomic instability. The adverse reaction is associated with rapid dosing or high dosage of haloperidol, chlorpromazine and fluphenazine. The occurrence and development of adverse reactions are also associated with dehydration, nutritional deficiencies, combined somatic diseases and hot climate. The management of this adverse reaction is to discontinue the antipsychotic and give symptomatic supportive treatment, which can be done with the muscle relaxant dantrolene and bromocriptine, which promotes central dopamine function.