Presence of fever in psychiatric patients may signify a number of potentially fatal conditions. Several of these are related to treatments (e.g. neuroleptic malignant syndrome with antipsychotics, serotonin syndrome with serotonergic antidepressants, and malignant hyperpyrexia with anaesthesia used for administration of electroconvulsive therapy) or exacerbated by them (e.g. malignant catatonia with antipsychotics). New classes of drug treatment may be changing the epidemiology of these disorders. We suggest that an initial diagnosis of hyperthermia syndrome is clinically useful as there are some important commonalities in treatment. We outline a systematic approach to identify a particular subtype of hyperthermia syndrome and the indications for more specific treatments where available.