When the body overheats above 40 degrees, it is called heat stroke. It’s a medical emergency. Here are the health risks and how to react right away.
This is one of the first dangers of extreme heat and heatwaves: heat stroke. This consequence is a sign of overheating of the body in the face of temperatures that are much too high for the body. Explanation.
Definition: what is heat stroke?
Heatstroke corresponds to overheating of the body with a temperature above 40 degrees. The body can no longer cope with the increase in internal temperature. We thus distinguish classic heatstroke in people exposed for a prolonged period to a hot and humid ambient temperature (for example, staying for hours in a car or in a RER in the heat) from exercise heatstroke which occurs after intense and sustained physical activity (classic heatstroke). Classic heat stroke occurs in epidemic form during heat waves, and predominates in elderly, fragile people suffering from chronic pathology: cardiovascular, pulmonary or mental.
What are the symptoms of heat stroke?
The diagnosis is based on hyperthermia and disturbances of consciousness after exposure to a hot and humid atmosphere. Among the symptoms of heat stroke:
- sudden fever that reaches or exceeds 40°c
- palpitations
- severe headache
- diffuse redness
- hot and very dry skin (sweating stops) / in athletes, the skin is hot and rather humid.
- vomiting
- diarrhea
- mental confusion, delirium, severe agitation
How long does heatstroke last?
In mild and quickly treated forms, heat stroke lasts less than 12 hours.
What to do in case of heat stroke?
You must seek medical assistance as soon as possible: call 15. Waiting :
- place the subject in the shade
- cool it by sprinkling it with cold water and fanning it
- or give a cold shower or a cool bath.
No adjuvant pharmacological treatment that can accelerate cooling has been shown to be effective.
What are the risks of heat stroke?
Heat stroke is a medical emergency because it can be life-threatening. It can cause neurological disorders (delirium, convulsions or coma) then so-called “multivisceral” failures and evolve towards death. Multi-organ failures are:
- Cardiovascular failure: arterial hypotension, shock
- Respiratory failure: polypnea, profound hypoxemia
- Renal failure: oligoanuria, moderate to severe renal failure.
- Hematological failure: hemostasis disorders with thrombocytopenia, even fibrinolysis and disseminated intravascular coagulation (DIC).
- Liver failure (rarer).
Among the most severe complications observed following heatstroke are:
- Acute coronary syndrome
- Heart rhythm disturbances, conduction disturbances.
- Bleeding complications
- Acute Respiratory Distress Syndrome (ARDS)
- Acute pancreatitis
- Fulminant hepatitis.
► Drink water regularly without waiting to feel thirsty (at least 1.5 L per day). The first people affected are infants and the elderly. The latter sometimes do not feel the sensation of thirst.
► Avoid physical exertion and sport which increase the internal temperature of your body.
► Wear light, loose clothing because they promote air circulation, rather light in color so as not to retain heat.
► Cool down several times a day : don’t hesitate to take showers, get your head wet, use misters or damp cloths.
► Fans? They provide a pleasant feeling of freshness through air circulation, but when the air is hot, it remains hot and does not refresh. It is best to get wet regularly.
► What to drink? Avoid alcohol, sugary drinks, and drinks with a high caffeine content (coffee, tea). Prefer still and sparkling water (enriched with salt) and fresh fruit juices.
► What to eat? Continue to eat normally, preferably focusing on fruits and vegetables: raw vegetable salads, fresh soups, but also dairy products (liquid yogurts, milkshakes, etc.).
► Cover your head. Your choice of hats, caps, or scarves will help you avoid sunstroke.
► Stay in well-ventilated and cool rooms. Close the shutters and open the windows to let the air through. If your apartment is really hot, arrange to stay in cool or air-conditioned places for at least two or three hours during the day (department stores, cinemas, public places).
- Heat stroke Heatstroke C. Rahmoune a, A. Bouchama b, Elsevier, 2004
- Heatwave recommendations, SFMU, 2011


