Heat Illness

On this page

Basics

• Summary
• Start Here
• Symptoms
• Prevention and Risk Factors
• Treatments and Therapies

Learn More

• Related Issues
• Specifics

See, Play and Learn

• Videos and Tutorials

Research

• Clinical Trials
• Journal Articles

Resources

• Find an Expert

For You

• Children
• Seniors
• Patient Handouts

Summary

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 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

Start Here

• Extreme Heat (Department of Homeland Security) Also in Spanish
• Frequently Asked Questions (FAQ) about Extreme Heat (Centers for Disease Control and Prevention)
• Hot Weather Safety for Older Adults (National Institute on Aging) Also in Spanish

Symptoms

• Warning Signs and Symptoms of Heat-Related Illness (Centers for Disease Control and Prevention) Also in Spanish

Prevention and Risk Factors

• Extreme Heat: A Prevention Guide to Promote Your Personal Health and Safety (Centers for Disease Control and Prevention)
• Heat Wave Safety Checklist (American Red Cross) - PDF

Treatments and Therapies

• Heat Cramps, First Aid (Logical Images)
• Heat Exhaustion, First Aid (Logical Images)
• Heatstroke, First Aid (Logical Images)

Related Issues

• Fitness: Stay Safe during Hot-Weather Exercise (Mayo Foundation for Medical Education and Research) Also in Spanish
• Protect Your Heart in the Heat (American Heart Association)

Specifics

• Heat Exhaustion and Heatstroke (American Academy of Family Physicians) Also in Spanish
• Heat Stress (National Institute for Occupational Safety and Health)
• Heat Waves (Healthy Roads Media) - PDF Also in Spanish
• Miliaria Rubra (Logical Images)

Videos and Tutorials

• Heat Waves (Healthy Roads Media) Also in Spanish
• Heat-Related Illnesses (American College of Emergency Physicians)

Clinical Trials

• ClinicalTrials.gov: Dehydration (National Institutes of Health)
• ClinicalTrials.gov: Heat Exhaustion (National Institutes of Health)
• ClinicalTrials.gov: Heat Stress Disorders (National Institutes of Health)

Journal Articles References and abstracts from MEDLINE/PubMed (National Library of Medicine)

• Article: Evaluation of Occupational Exposure Limits for Heat Stress in Outdoor...
• Article: A hemicyanine based ratiometric fluorescence probe for mapping lysosomal pH...
• Article: Fulminant liver failure in a street runner: Effects of heat...
• Heat Illness -- see more articles

Find an Expert

• American Red Cross Also in Spanish
• Centers for Disease Control and Prevention Also in Spanish
• National Center for Environmental Health (Centers for Disease Control and Prevention)
• National Institute for Occupational Safety and Health Also in Spanish
• National Institute on Aging Also in Spanish

Children

• Children in Hot Cars Result in Fatal Consequences (American College of Emergency Physicians)
• Miliaria Rubra (Logical Images)
• Parents' and Coaches' Guide to Dehydration and Other Heat Illnesses in Children (National Athletic Trainers' Association) - PDF Also in Spanish

Seniors

• Exercising Safely in Hot Weather (National Institute on Aging) - PDF
• Heat Stress in Older Adults (Centers for Disease Control and Prevention) Also in Spanish
• Hot Weather Safety for Older Adults (National Institute on Aging) Also in Spanish

Patient Handouts

• 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)
• Protecting Yourself from Heat Stress (National Institute for Occupational Safety and Health) - PDF Also in Spanish