Sunstroke and diarrhoea: what to know

Sunstroke, also called heat stroke, is a medical emergency in which the body cannot control its temperature. Heat stress, sweating, and fluid loss may upset the gut. Diarrhoea can also begin for a separate reason, such as food poisoning, gastroenteritis, food intolerance, or another bowel condition. The diarrhoea itself does not show that sunstroke is the cause.

Warning signs include confusion, fainting, unusual drowsiness, a seizure, very hot skin, or inability to drink. These signs need urgent medical help because dehydration and heat injury can affect the brain, circulation, and kidneys.

Move the person to a cool, shaded or air-conditioned place and remove extra clothing. Cool the skin with water, wet cloths, or airflow. If the person is fully awake and can swallow safely, offer frequent small sips of an oral rehydration drink. Do not force fluids into someone who is confused, vomiting repeatedly, or too drowsy to swallow.

Avoid alcohol and strenuous activity. Once stable, choose simple foods if tolerated and keep monitoring urine, alertness, and stool frequency. A clinician may need to assess dehydration, temperature control, and the cause of diarrhoea.

Call emergency services if there is confusion, collapse, a seizure, severe weakness, trouble breathing, hot skin with altered behaviour, or inability to drink. Seek same-day medical care for ongoing diarrhoea with very little urine, dizziness on standing, blood in the stool, severe abdominal pain, repeated vomiting, or symptoms after substantial heat exposure. Do not wait for diarrhoea to settle if heat stroke is suspected.

Ask what caused the diarrhoea, which rehydration drink is suitable, whether medicines should be paused, and which symptoms should trigger reassessment. Tell the clinician when heat exposure began, how often stools occurred, what fluids were kept down, and whether urine became darker or less frequent.