Heat exhaustion symptoms

The body loses water and electrolytes through sweating and may struggle to cool itself. Someone may feel faint, tired, irritable or unable to continue activity. Urine can become darker and less frequent as fluid loss grows. Symptoms often begin during hot work, exercise or time in a poorly ventilated place. [Heat Exhaustion](/conditions/heat-exhaustion/) can overlap with [Dehydration](/conditions/dehydration/), so the whole pattern matters rather than one symptom alone.

Stop activity and move to a cool place. Lie down if light-headed, loosen clothing, cool the skin with wet cloths or a fan, and take small sips of water or an oral rehydration drink if fully alert. Avoid alcohol and further heat. Ask another person to stay nearby while symptoms settle. Learn more about [Excessive Sweating](/symptoms/excessive-sweating/), [Excessive Thirst](/symptoms/excessive-thirst/) and [Heat Intolerance](/symptoms/heat-intolerance/).

Call emergency services for confusion, fainting, seizure, severe breathing trouble, inability to drink, repeated vomiting or a person who is difficult to wake. Very hot skin with worsening symptoms may signal heatstroke, which needs immediate care. If symptoms do not improve after cooling and fluids, contact a clinician promptly. A severe [Headache](/symptoms/headache/), persistent [Dizziness](/symptoms/dizziness/) or marked [Dark Urine](/symptoms/dark-urine/) should be assessed.

Ask which symptoms suggest heat exhaustion, how to prevent another episode, when to resume exertion, and whether a medical condition or medicine changes your risk.