Heat Exhaustion vs. Heat Stroke Topic Guide

Heat exhaustion and heat stroke are heat-related illnesses. Other heat-related illnesses include heat cramps, heat syncope (fainting), and heat rash. Heat stroke is the most severe form of these conditions, and requires immediate medical treatment by calling 911.

Heat exhaustion usually occurs when you play or work in a hot, humid environment and you lose fluids through sweat. This causes the body to overheat and become dehydrated. In heat exhaustion, the body temperature may be high, but not above 104 F (40 C), and medical treatment may be necessary. In contrast, heat stroke (also called heatstroke, sunstroke, or sun stroke) is a life-threatening medical emergency. It usually develops from heat exhaustion, and the internal body temperature rises to the point at which brain damage or damage to other internal organs may result (internal body temperature may reach 105 F or greater [40.5 C or greater).

Common symptoms and warning signs of these two heat-related illnesses are nausea, skin flushing, headache, dizziness, weakness, thirst, muscle cramps, and rapid heart rate.

Heat exhaustion can be treated with rehydration at home or through IV at the doctor's office, Urgent Care, or Emergency Department. Heat stroke is a condition that needs to be treated right away. If you think someone you know is suffering from heat stroke call 911 immediately and get medical help. If medical treatment isn't started urgently, the person may die.