Signs of Heat Stress in Humans

Heat stress occurs when the body gains heat faster than it can lose it. Early symptoms may be thirst, tiredness, sweating, prickly skin, cramps, headache, or light-headedness. Heat exhaustion can bring marked weakness, nausea, vomiting, clammy skin, and faintness. Confusion, unusual behaviour, seizures, loss of consciousness, or very hot skin are danger signs of heat stroke, which can damage the brain and other organs. A fever from infection is different, although both can raise body temperature.

Move the person to a cool, shaded or air-conditioned place and remove unnecessary outer clothing. Help them rest and cool the skin with water, wet cloths, or gentle airflow. If they are awake and able to swallow, offer small, frequent sips of cool fluid. Do not give drinks to someone who is confused, vomiting repeatedly, having a seizure, or unable to swallow. Stop exercise and avoid returning to heat until fully recovered.

Call emergency services immediately for confusion, a seizure, collapse, loss of consciousness, severe breathing difficulty, or suspected heat stroke. Get urgent assessment if the person cannot drink, keeps vomiting, becomes faint, or does not improve quickly after cooling. People with serious medical conditions, those taking medicines that affect sweating or fluid balance, older adults, and young children may need help earlier.

Ask whether medicines or a health condition increase heat sensitivity, how much activity is safe in hot weather, and which hydration plan fits your needs. Ask when symptoms should be reviewed after an episode.