Why does heat exhaustion cause heat intolerance?

Sweating and increased blood flow to the skin normally help release heat. In a hot, humid setting, or after prolonged exertion, those measures may no longer keep pace with heat gain. Fluid and salt loss can add weakness, dizziness and a racing heartbeat, making another warm room or short walk feel overwhelming. Heat Intolerance is a common presentation of Heat Exhaustion; it is not, by itself, enough to identify the cause.

Leave the heat as soon as possible and rest somewhere cool with moving air. Remove unnecessary layers, use cool damp cloths on the skin and avoid hot showers. Drink small amounts regularly if you are alert, not vomiting and able to swallow. Pause driving, sport and physical work while you are dizzy, weak or unable to cope with warmth. A companion can help monitor whether you are improving.

Call emergency services for confusion, collapse, seizure, inability to stay awake, severe breathlessness or a person who seems markedly unwell in the heat. Obtain same-day medical advice if symptoms persist after cooling and resting, vomiting limits fluids, or you have a significant medical condition that affects your heart, kidneys or fluid balance. Worsening symptoms need urgent assessment.

Discuss whether any regular medicines can reduce sweating, change fluid balance or make hot conditions harder to manage. Ask how to adapt work, fasting, travel or exercise plans during very warm weather.