Heat Exhaustion vs Heat Stroke: Symptoms and Emergency Actions
Heat exhaustion commonly causes heavy sweating, weakness, dizziness, headache, nausea and thirst. Confusion, slurred speech, seizures or loss of consciousness can signal heat stroke, a medical emergency that requires an immediate emergency call and rapid cooling.
Timeline
- At the first symptoms: Stop activity, move to a cooler place, remove excess clothing and begin cooling.
- If the person is alert: For suspected heat exhaustion, offer small sips of water and watch closely for worsening symptoms.
- If thinking, speech or consciousness changes: Call emergency services immediately and continue active cooling while help is coming.
Heat exhaustion and heat stroke sit on a spectrum of heat-related illness, and their symptoms can overlap. Heat exhaustion usually reflects water and salt loss during heavy sweating. Heat stroke occurs when the body can no longer control its temperature and can cause death or permanent disability. A person can deteriorate quickly, so first aid should start as soon as unusual symptoms appear rather than waiting to make a perfect diagnosis. [1][2][3]
Common heat-exhaustion signs include heavy sweating, weakness or fatigue, headache, dizziness or lightheadedness, nausea or vomiting, thirst and irritability. Skin may be cool and moist, and the pulse or body temperature may be elevated. These findings are clues rather than a checklist: heat illness may look different from person to person, and a worker, athlete or traveler who feels unwell in the heat should stop exertion and be assessed. [1][2][3]
Heat stroke becomes especially likely when the brain is affected. Confusion, slurred speech, loss of coordination, seizure, fainting or unconsciousness are emergency warning signs. Very high body temperature and a rapid pulse may occur. Do not rule out heat stroke because the person is sweating: OSHA and CDC materials both note that skin may be hot and dry or that profuse sweating may continue. When in doubt, cool the person and call emergency services. [1][2][3]
For suspected heat exhaustion, stop activity and move the person into shade or air conditioning. Loosen or remove unnecessary outer clothing and cool the skin with wet cloths, water and moving air. If the person is fully alert, able to swallow and not vomiting, offer frequent small sips of cool water. Stay with the person because symptoms can worsen. Seek medical help promptly if vomiting occurs, symptoms get worse, or they do not improve within about an hour. [1][2][4]
For suspected heat stroke, call the local emergency number immediately, then cool first while help is on the way. Move the person to a cooler area, remove outer clothing, wet as much skin as practical, fan the body, and place cold wet towels or ice packs around the head, neck, trunk, armpits and groin. Where trained helpers and safe equipment are available, cold-water immersion is an effective rapid-cooling method. Follow the dispatcher’s instructions and never leave the person alone. [1][2][3]
Do not give food, pills or drinks to someone who is confused, having a seizure, unconscious or unable to swallow safely. Do not delay the emergency call to search for a thermometer, and do not treat heat stroke as an ordinary fever with fever-reducing medicine. If the person becomes unresponsive and is not breathing normally, begin CPR if trained and use an automated external defibrillator if available, while another person continues to coordinate emergency help. [2][4]
Prevention still matters after recovery. Ease into strenuous work over several days, schedule breaks, use shade or air conditioning, drink regularly, and use a buddy system because judgment may decline as heat illness develops. Age, pregnancy, heart or other chronic conditions, certain medicines, protective clothing and lack of acclimatization can increase risk. People with medical conditions or fluid restrictions should follow a clinician’s heat plan and current local public-health advice rather than a generic fluid target. [2][3][5]
Sources
- CDC — Heat-Related Illnesses: What to Look For and What to Do
- OSHA — Heat-Related Illnesses and First Aid
- CDC/NIOSH — Protecting Yourself from Heat Stress
- OSHA — Heat Illnesses and First Aid
- CDC — About Heat and Your Health