How to Manage Heat Exhaustion and Heat Stroke

Heat-related illness — ranging from mild heat cramps to life-threatening heat stroke — kills approximately 700 Americans each year and sends tens of thousands to emergency rooms. As climate change increases the frequency and intensity of heat waves, heat illness is a growing public health threat. Understanding the spectrum of heat-related illness, how to recognize heat exhaustion before it progresses to the far more dangerous heat stroke, and what to do in both situations can save lives.

THE BODY'S HEAT REGULATION SYSTEM

The body continuously generates heat as a byproduct of metabolism and physical activity. Core body temperature must be maintained within a narrow range (approximately 97–99°F / 36.1–37.2°C) — even modest elevations above this range begin impairing enzyme function; temperatures above 104°F (40°C) cause cellular damage throughout the body; temperatures above 106–108°F (41–42°C) can cause brain damage and death.

To manage heat, the body uses:

• Sweat evaporation: The primary cooling mechanism — sweat evaporating from the skin surface removes heat. This requires adequate hydration.
• Cutaneous vasodilation: Increasing blood flow to the skin surface allows heat dissipation.
• Respiration: Some heat is lost through breathing.