Headache and nausea from heat: what should you know?

Sweating removes fluid and salts, while hot surroundings make it harder for the body to release heat. This can produce headache, nausea, thirst, weakness, dizziness, cramps, and heavy sweating. Heat exhaustion can worsen if activity continues. Hot weather is also more stressful when you are ill, taking certain medicines, or unable to drink. Headache and nausea after heat exposure do not by themselves show how serious the illness is, so mental state, temperature, sweating, and response to cooling are useful clues.

Stop activity and move into air conditioning or shade. Remove extra clothing, lie down, and cool the skin with wet cloths, a fan, or a cool shower. Sip water or an oral rehydration drink if you are awake and not vomiting. Avoid alcohol. Do not return to strenuous activity until fully recovered. If vomiting prevents fluids, arrange medical help rather than forcing drinks.

Call emergency services for confusion, unusual behaviour, fainting, a seizure, severe weakness, loss of coordination, hot skin, or inability to drink. Obtain urgent medical advice if symptoms persist after cooling, vomiting continues, or the headache becomes severe. Children, older adults, pregnant people, and those with chronic illness may need a lower threshold for assessment.

Was this heat exhaustion or another illness? How should I replace fluids, review medicines, and plan a safe return to activity?