What does heat intolerance feel like with heat exhaustion?

Heat exhaustion develops when the body struggles to cool itself and replace fluid and salt lost through sweating. You may feel intensely hot, tired, weak, light-headed, headachy, or nauseated. The skin may be sweaty and clammy, and you may have thirst, muscle cramps, a fast pulse, or difficulty continuing activity in a warm place.

Symptoms can build during outdoor work, exercise, travel, or time in a poorly ventilated space. Heat intolerance can also have other causes, so a pattern that occurs outside acute heat exposure should be discussed with a clinician. During an episode, the immediate priority is cooling and safe observation.

Stop exertion and move to a cool or shaded place. Remove unnecessary outer clothing, cool the skin with wet cloths or a fan, and take small, frequent sips of cool water if the person is awake and able to swallow. Rest while someone stays nearby and watches for improvement. Do not return to strenuous activity until you have recovered and have advice if episodes recur.

If vomiting prevents drinking, symptoms do not improve with cooling, or the person has a medical condition affecting fluid balance, seek medical advice promptly. A clinician can review medicines, thyroid symptoms, infection, and other contributors to repeated heat sensitivity.

Call emergency services for confusion, unusual behaviour, loss of consciousness, seizures, very hot skin, or inability to drink. These may indicate heatstroke, which is an emergency. Seek prompt care if weakness, dizziness, vomiting, or headache persists after cooling, or if the person is pregnant, very young, older, or has a condition that increases heat risk.

Could my medicines or another health problem be affecting heat tolerance? How should I prepare for work, exercise, or travel in hot weather? What early symptoms mean I should stop activity and seek help?