Heat waves should be considered as a medical emergency; during some recent heat waves in France and other countries, thousands of people have died. Most of the deaths were from elderly people in non-air conditioned homes and thus dying of heat stroke or other complications. Many of us have probably felt the more common but less serious heat exhaustion, with symptoms of dizziness, weakness, nausea, headaches, among others.
The American Family Physician journal has a nice review article for you to review (Management of Heatstroke and Heat Exhaustion) which talks about the different clinical levels of the much more common heat exhaustion, and the much more serious heat stroke:
…Classic heatstroke is caused by environmental exposure and results in core hyperthermia above 40°C (104°F). This condition primarily occurs in the elderly and those with chronic illness. Classic heatstroke can develop slowly over several days and can present with minimally elevated core temperatures. It is associated with central nervous system dysfunction including delirium, convulsions, and coma, making it difficult to distinguish from sepsis. These manifestations are thought to be an encephalopathic response to a systemic inflammatory cascade.4
Exertional heatstroke is a condition primarily affecting younger, active persons. It is characterized by rapid onset—developing in hours—and frequently is associated with high core temperatures.
Heat exhaustion is a more common and less extreme manifestation of heat-related illness in which the core temperature is between 37°C (98.6°F) and 40°C. Symptoms of heat exhaustion are milder than those of heatstroke, and include dizziness, thirst, weakness, headache, and malaise. Patients with heat exhaustion lack the profound central nervous system derangement found in those with heatstroke. Their symptoms typically resolve promptly with proper hydration and cooling….
As for treatment, we’ve probably all seen TV shows showing heat stroke people being put into cold baths — but the better choice is simpler, with evaporation therapy, by simply toweling off or spraying yourself with water, and adding a fan if possible. This is the quickest way to cool off. But the #1 treatment remains hydration. And definitely go see your doctor if you or a loved one (especially elderly or very young) feel really dehydrated — or especially if you or they have any serious mental status changes like delerium or lethargy.
And don’t forget the obvious choice of avoiding major heat in the first place, and immediately finding cool spots if you start to feel symptoms of heat exhaustion. A couple nights ago my apartment complex playground was eerily empty at dinnertime, but since it was still 41 degrees, parents were making wise decisions for their kids by keeping them inside.