Summer heat illnesses. Conditions that range from mild to fatal.

Heat illness varies in severity from mild to life-threatening. Basic treatment includes rapid cooling and restoration of fluid and electrolyte balance. Most patients can be treated definitively in the field. Some require additional therapy in a hospital emergency department, and a few need hospitalization. Not all hyperthermic patients have heatstroke. Neuroleptic malignant syndrome is a possibility, or a patient with a febrile illness may also present on a hot day. Careful evaluation is therefore necessary before the diagnosis of simple heatstroke is considered acceptable.