Heatwave: how to spot heatstroke

Every heatwave sends searches for “heatstroke symptoms” soaring. The reason is simple: heat does not strike all at once, it builds up in stages, and the shift from one stage to the next can be very quick in vulnerable people. Telling those stages apart is what allows you to react at the right moment, before the situation becomes an emergency.

Stage one, heat cramps. These are muscle pains that appear after exertion in the heat, often linked to the salt lost through sweat. They mostly affect the calves, thighs and abdomen. The right response is to stop the activity, get somewhere cool, drink water and eat something salty. Going back to the effort too soon is the main mistake.

Stage two, heat exhaustion. The signs are clearer: intense fatigue, headache, nausea, clammy pale skin, rapid pulse, dizziness, sometimes vomiting. Body temperature usually stays below 40 °C (104 °F). Lay the person down somewhere cool with legs slightly raised, cool them with a damp cloth and moving air, and give small sips of water if they are fully conscious.

Stage three, heatstroke: a life-threatening emergency, and what separates it from the previous stage is above all the state of consciousness. Temperature rises above 40 °C, the skin may become hot and dry, the person is confused, aggressive or drowsy, sometimes unconscious or having seizures. Call emergency services immediately and start cooling the body without waiting for them: move to shade, remove clothing, cool water on the skin, continuous fanning.

Two important precautions: never give fluids to someone who is unconscious or confused, and do not plunge an unconscious person straight into iced water. Cooling should be vigorous but progressive while waiting for medical care.

The most exposed are infants, older adults, pregnant women, outdoor workers, endurance athletes and people on certain medications — diuretics, antipsychotics, antidepressants — that disrupt temperature regulation or the sensation of thirst. In older adults that sensation is naturally dulled, so offer drinks regularly rather than waiting to be asked.

Two safety reminders that are often forgotten: never leave a child, an older person or an animal in a parked car, where the temperature climbs dangerously within minutes; and check how your medicines should be stored, since some lose their properties above 25 °C.

On prevention, the widely agreed steps are simple: drink regularly without waiting for thirst, avoid alcohol and exertion during the hottest hours, close shutters and windows by day then ventilate at night, spend two to three hours a day somewhere cool or air-conditioned, and check on isolated relatives. Your national public-health authority’s guidance is the reference; if in doubt about a symptom, contact a health professional or your local emergency number.