Acute heat illnesses
Suspect always heatstroke when physical activity is accompanied by hot skin, altered consciousness, hypotension, hyperventilation, nausea or diarrhoea. Sweating may be excessive but will stop especially when dehydration develops. Measure the rectal temperature to distinguish between heatstroke and less severe heat illnesses (in heatstroke rectal temperature is usually over 39°C.) Axillary or ear temperature are not informative when examining a patient with a suspected heat illness. In heatstroke the first aid is cooling, which must be started without delay.