Your body normally cools itself by sweating. During hot weather, especially when it is very humid, sweating just isn't enough to cool you off. Your body temperature can rise to dangerous levels and you can develop a heat illness.
Most heat illnesses happen when you stay out in the heat too long. Exercising and working outside in high heat can also lead to heat illness. Older adults, young children, and those who are sick or overweight are most at risk. Taking certain medicines or drinking alcohol can also raise your risk.
Heat-related illnesses include:
- Heat stroke - a life-threatening illness in which body temperature may rise above 106 °F (41 °C) in minutes. Symptoms include dry skin, a rapid, strong pulse, dizziness, nausea, and confusion. If you see any of these signs, get medical help right away.
- Heat exhaustion - an illness that can happen after several days of exposure to high temperatures and not enough fluids. Symptoms include heavy sweating, rapid breathing, and a fast, weak pulse. If it is not treated, it can turn into heat stroke.
- Heat cramps - muscle pains or spasms that happen during heavy exercise. You usually get them in your abdomen, arms, or legs.
- Heat rash - skin irritation from excessive sweating. It is more common in young children.
You can lower your risk of heat illness by drinking fluids to prevent dehydration, replacing lost salt and minerals, and limiting your time in the heat.
Centers for Disease Control and Prevention
- Warning Signs and Symptoms of Heat-Related Illness (Centers for Disease Control and Prevention) Also in Spanish
Videos and Tutorials
- Heat-Related Illnesses (American College of Emergency Physicians)
Journal Articles References and abstracts from MEDLINE/PubMed (National Library of Medicine)
- Article: Measuring Heat Stress for Human Health in Cities: A Low-Cost Prototype...
- Article: Vitexin Regulates Heat Shock Protein Expression by Modulating ROS Levels Thereby...
- Article: Comparison of Transcriptomic Changes in Survivors of Exertional Heat Illness with...
- Heat Illness -- see more articles
Find an Expert
- Heat emergencies (Medical Encyclopedia) Also in Spanish
- How to avoid overheating during exercise (Medical Encyclopedia) Also in Spanish
- Protecting Workers from Heat Stress (Occupational Safety and Health Administration) - PDF
- Protecting Yourself from Heat Stress (National Institute for Occupational Safety and Health) - PDF Also in Spanish