Heat exhaustion and heatstroke – telling them apart

Heat exhaustion is the body struggling to cope. Heatstroke is the body's temperature control having failed, and it damages the brain, kidneys and other organs within a short time. They sit on the same spectrum, and heat exhaustion left untreated becomes heatstroke.

The single most useful distinguishing sign is the state of mind. Someone with heat exhaustion is uncomfortable but making sense. Someone confused, aggressive, slurring, staggering or unconscious has heatstroke until proven otherwise.

• Heavy sweating, pale and clammy skin.
• Headache, dizziness, feeling faint.
• Nausea, sometimes vomiting.
• Muscle cramps, particularly in the legs and abdomen.
• Fast, weak pulse and fast breathing.
• Feeling extremely tired and weak — but still oriented and able to answer questions.

1. 1Move them into shade or a cool room and get them lying down with their legs slightly raised.
2. 2Loosen or remove excess clothing.
3. 3Cool the skin — a wet cloth, a fan, cool water on the neck, armpits and groin.
4. 4Give cool water to sip, or an oral rehydration solution. Not alcohol, and not a strong energy drink.
5. 5Watch them. They should improve noticeably within half an hour.

• Confusion, strange behaviour, slurred speech, staggering, seizures or loss of consciousness.
• Very hot skin. It may be dry, because sweating has stopped — but it can still be sweaty in someone who was exerting themselves, so do not rule it out on that.
• A body temperature above 40 °C.
• Fast, strong pulse and rapid shallow breathing.
• Not passing urine, or very dark urine.

1. 1Call an ambulance immediately.
2. 2Start cooling straight away while you wait — this is the treatment, and every minute at a high temperature causes more damage.
3. 3Get them into shade, remove outer clothing, and soak them with water. A cool bath or shower, wet sheets, or repeated dousing all work.
4. 4Fan them continuously while wet — evaporation removes far more heat than water alone.
5. 5Put ice packs or cold bottles at the neck, armpits and groin if available.
6. 6Do not give anything by mouth to someone who is confused or drowsy — they may choke.
7. 7If they are unconscious but breathing, put them on their side.

• ambulance10177Emergency Medical Services
• local_police10111South African Police Service
• sos112Universal Emergency (mobile)
• psychology0800 029 999SADAG Mental Health Crisis Line
• science0861 554 911Poisons Information Helpline

• Babies and small children, who heat up faster and cannot say what is wrong.
• Adults over 65, particularly those living alone.
• People working outdoors — construction, farming, security, waste collection.
• Anyone exercising or playing sport in the heat, especially when unaccustomed to it.
• People with heart, lung or kidney disease, or diabetes.
• People on water tablets, some blood pressure medicines, antihistamines, antidepressants and antipsychotics, several of which reduce sweating or fluid reserve.
• Anyone who has been drinking alcohol.