Heat Stroke & Heat Exhaustion
Heat stroke is a true emergency in which the body's temperature control fails. Confusion in a hot, collapsed person means cool them aggressively, right now.
When to call an ambulance immediately
- Confusion, agitation, slurred speech, seizures or unconsciousness
- Body temperature above 40°C
- Skin that is hot to touch, whether dry or still sweating
- A fast, strong pulse and rapid breathing
- Vomiting, and passing very little or very dark urine
- Symptoms in an infant, an older adult, an outdoor worker, or anyone taking psychiatric or blood pressure medication
What to do
Work through these in order. If you are alone, put your phone on speaker so the 108 call handler can guide you while your hands stay free.
- 1
Distinguish exhaustion from stroke by the mental state
Heat exhaustion means heavy sweating, weakness, headache, nausea and cramps, with a clear mind. Heat stroke means the person is confused, behaving oddly, or unconscious. That change in mental state is the line between the two, and it is what makes it an emergency.
- 2
Get them out of the heat immediately
Move into shade or an air-conditioned room. Remove excess clothing and any protective gear.
- 3
Cool aggressively — this is the treatment
The single most effective method is immersing the body in cold water where that is possible. If not, soak them thoroughly with cool water, apply wet cloths over the whole body, and fan them continuously to drive evaporation. Place ice packs at the neck, armpits and groin. Keep cooling until they are alert and the skin feels cool.
- 4
Call 108 while cooling, not before
Do not stop cooling to make the call, and do not delay cooling until the ambulance arrives. The speed of cooling in the first thirty minutes is what determines survival and whether there is lasting brain injury.
- 5
Give fluids only if fully alert
If they are conscious, oriented and able to swallow safely, give cool water or oral rehydration solution in small sips.
- 6
Position and monitor
If unconscious but breathing, use the recovery position. Watch the breathing continuously and be ready to start CPR.
Never do these
Most of these are well-intentioned and widely believed. All of them make the situation worse.
- Never give fluids by mouth to a confused or unconscious person. It will go into the lungs.
- Never give paracetamol or ibuprofen for heat stroke. They lower fever caused by infection and do nothing here, and they can worsen liver and kidney injury.
- Never stop cooling because the person shivers. Shivering is expected, and cooling should continue.
- Never leave anyone, especially a child, in a parked car even briefly. Interior temperatures rise to lethal levels within minutes.
- Never assume dry skin is required for the diagnosis. Exertional heat stroke in young, fit people frequently presents with the person still sweating heavily.
Once the immediate danger has passed
- Everyone with heat stroke needs hospital assessment, because kidney injury, muscle breakdown and clotting problems can develop over the following hours.
- For the next several days they will be more vulnerable to heat, so they should avoid strenuous work in hot conditions.
- In a Punjab summer, plan outdoor work for early morning, drink before you feel thirsty, and check on elderly neighbours during a heat wave.
Frequently asked
Is cold water immersion dangerous?
For heat stroke it is the most effective treatment available and is recommended where it can be done safely. The theoretical concerns about shock are outweighed by the proven benefit of cooling fast.
How is this different from ordinary dehydration?
Dehydration makes you thirsty, tired and light-headed but leaves your thinking intact. Heat stroke changes how the brain works. If someone in the heat starts talking nonsense, that is the emergency.
Reviewed and written by
Dr. Poonam Sekhon Chahal, MBBS, MEM
Senior Emergency Physician, Manipal Hospital, Patiala · Certified in ACLS, ATLS, PALS and PoCUS