Overexposure to heat, particularly with humidity, can lead to a heat-related illness, which can be as mild as heat cramps, or as severe and potentially fatal as heat stroke. The body’s adaptation process to heat can take from one to several weeks. The danger of heat injury increases with humidity and age, or if one has ingested alcohol or certain drugs. In hot climates, the body’s main defence against heat is perspiration. IN THE ABSENCE OF STRENUOUS EXERCISE, the average person must replace at least 1.5 liters of fluid per day in hot weather; by the time you feel thirsty, you are already becoming dehydrated, sweat contains a high concentration of salt, which also must be replaced by eating salty foods, or adding salt to your food.
Heat cramps are painful muscle spasms due to fluid and salt imbalance and frequently occur after strenuous exercise in hot weather. A high level of humidity, recent ingestion of alcohol, or being over the age of forty may increase the likelihood of developing heat cramps. For those who are exercising (playing tennis, golf, hiking) in hot weather, fluid and salt replacement are paramount; Gatorade is a good commercial preparation that addresses this issue. Treat by getting the person into the shade; have them gently stretch the affected muscle; encourage them to drink tomato/orange juice or Gatorade (to replace electrolytes) – don’t overdo the water, since this may further dilute the salt levels in the body; sponge down with a cool damp cloth.
Heat exhaustion is characterized by excessive sweating, fatigue, dizziness, headache, nausea, and sometimes by vomiting, cramps and fainting; the initial signs occur when dehydration occurs. This is a more urgent situation that requires replacement of fluids and salt, as well as removing the individual from direct sunlight and cooling him down.
Heat stroke is quite dangerous, potentially fatal, and requires emergency treatment. An older person may be affected even without exercising. The person has lost the ability to sweat, the body temperature becomes dangerously elevated, and if not treated, the person may become comatose and die; this situation usually requires emergency medical attention, which includes rapid cooling, in a hospital setting. One way that this condition can be differentiated from heat exhaustion is that the person’s skin is hot, flushed and very dry – his body has lost the ability to sweat; the individual will have a rapid pulse and a fever, up to 106F; brain damage may occur.
Certain drugs, like antihistamines, can increase the susceptibility to heat stroke, which is usually of abrupt onset.