1. Diuretic and some psychiatric drugs can prevent the body from losing heat quickly.
2. People who are obese or old hav​e to be particularly careful not to dehydrate or overheat. Old people may not be able to move about easily, turn on the fan or air conditioner when the weather gets too hot, or drink as frequently as they should. But drinking enough water and sitting in a cool environment are important in hot weather.
3. When training for a marathon, be sure to practise outside to get used to weather conditions. Running in the gym is vastly different from running in hot, humid weather.
4. While proper hydration is crucial before marathons, or before any exercise, water may not be best as it doesn’t help replace the salts lost through sweating. An imbalance of salts leads to cramps or weakness of the arms. Isotonic drinks may be better.
5. Avoid exercise when feeling unwell, as it can make you more likely to suffer from heat exhaustion.
6. A quick way of cooling the body is to dip a sponge or towel in cold water and press it on the neck, armpits and groin area. If heat symptoms persist, seek medical attention immediately.
7. Thirst is not as good an indicator of dehydration as the colour of the urine. A clear colour means the body is well hydrated.
8. People suffering from multiple long-term medical conditions such as hypertension and diabetes should get out of saunas, hot tubs or steam rooms when they feel giddy or faint, have a headache, nausea or cramps. It’s best to go with ​someone who is able to help you if you suddenly feel sick.

Ref: N18