Narong Sahametapat, public health permanent secretary, said the risk groups were outdoor workers, children aged below five and the elderly, people with high blood pressure, obese people, sleep-deprived individuals and heavy drinkers.
Heat stroke occurs when the body is unable to control its temperature. It can cause death or permanent disability if not treated promptly. The symptoms include high body temperature, throbbing headache, dizziness, irregular heartbeat and shock.
Department of Disease Control (DDC) director-general Sopon Mekthon said heat stroke often developed from milder heat-related illnesses such as sun burn, heat cramps and heat exhaustion.
With the temperature climbing above 40 degrees Celsius in some areas now, Dr Sopon suggested people wear light-coloured, loose-fitting clothing made of breathable fabric, avoid vigorous physical outdoor activities, drink plenty of water and never leave children or the elderly in a closed car.
Heat stroke has claimed 196 lives since 2003, 20 of which occurred between March and April last year. Most of the fatalities are elderly people with chronic health conditions or heavy drinkers, according to Bureau of Epidemiology.
Dr Sopon said first-aid measures included moving the person to a cool, shaded area and lying them down with both legs lifted to increase upward blood circulation. They should be cooled if possible -- either by soaking their clothes with water, sponging or fanning — before being taken to hospital.
The patient with mild symptoms are advised to drink a lot of water, he said.