Heat cramps, heat exhaustion and heat stroke

Heat cramps cause painful muscle tightening after heat and sweating. Heat exhaustion can add weakness, headache, nausea, thirst, dizziness and heavy sweating; see [Heat Exhaustion](/conditions/heat-exhaustion/) for more detail. Heat stroke is an emergency in which the body cannot control its temperature and brain function may change, causing confusion, collapse or seizure. [Excessive Sweating](/symptoms/excessive-sweating/) and [Excessive Thirst](/symptoms/excessive-thirst/) suggest fluid loss but do not measure severity. [Dehydration](/conditions/dehydration/) can accompany any stage.

For cramps or suspected exhaustion, stop activity, move to a cool place, loosen clothing and cool the skin with wet cloths or a fan. If the person is alert and swallowing normally, give small sips of fluid. If heat stroke is possible, call emergency services immediately, cool the person rapidly and do not give drinks to someone who is confused, vomiting or unable to swallow. Do not wait for every symptom to appear.

Emergency care is needed for confusion, fainting, seizure, unusual behaviour, severe weakness, breathing difficulty or a very hot body. Seek prompt assessment when [Dizziness](/symptoms/dizziness/), [Headache](/symptoms/headache/), [Dark Urine](/symptoms/dark-urine/) or ongoing vomiting follows heat exposure. Move indoors and stop exertion while help is arranged.

Ask how your medicines, health conditions, work setting and previous heat illness affect risk. Discuss a hydration and cooling plan, and mention any [Heat Intolerance](/symptoms/heat-intolerance/) or repeated symptoms.