Acute heat exhaustion: what to know and do

Move out of the heat, loosen unnecessary clothing and cool the skin with wet cloths, a fan or a cool shower. If the person is awake and not vomiting, offer frequent sips of water or an oral rehydration drink.

Heavy sweating reduces circulating fluid and salts while the body struggles to release heat. Heat exhaustion can present with dizziness, headache, thirst, weakness, nausea, muscle cramps, clammy skin or a fast pulse. Dark urine or passing less urine can point to dehydration.

A person may feel faint but should remain able to respond. Confusion, collapse, a seizure or severely altered behaviour suggests a more dangerous heat illness and changes the response from home cooling to emergency care.

Help the person lie down in an air-conditioned or shaded place and stay with them. Apply cool water to the skin, fan them and place cool packs wrapped in cloth around the neck and underarms. Avoid alcohol and strenuous activity while symptoms settle.

Give small, repeated sips rather than forcing a large drink. Do not give anything by mouth if the person is drowsy, confused, having a seizure or unable to swallow safely. Arrange a medical assessment if symptoms are not clearly improving after cooling and fluids.

Call emergency services for confusion, fainting that does not quickly resolve, seizure, severe breathing difficulty, inability to drink, repeated vomiting or rapidly worsening symptoms. Continue active cooling while help is on the way, and place an unconscious person who is breathing on their side.

Seek prompt clinical advice for ongoing dizziness, very dark urine, reduced urination, significant medical conditions or medicines that affect fluid balance. Children, older adults and pregnant people may need earlier assessment because dehydration can become harder to correct safely.

Ask whether your symptoms suggest dehydration, whether any regular medicines alter sweating or fluid balance, and when you can return to work or exercise. Discuss a heat plan if you work outdoors, exercise in hot conditions or have had repeated episodes.