New Delhi, May 20 (IANS): As the mercury levels are soaring in north India, being out in the sweltering heat can result in heat stroke which can be extremely harmful, even fatal, says an expert.

Heat stroke is caused due to prolonged exposure to higher temperatures (above 40 degrees Celcius) or physical exertion. It usually occurs in combination with dehydration. 

"If left untreated, heat stroke can affect vital organs and can prove fatal in severe cases," said Dr Raman Abhi, additional director (internal medicine) at Fortis Memorial Research Institute in the capital.

Sudden rise in body temperature, rapid heartbeat, which may be either strong or weak, rapid or shallow breathing, unconsciousness, lack of sweat, throbbing headache, dizziness, nausea, vomiting and seizures are some of the symptoms of heat stroke, Abhi added.

The skin may lose its moisture and water retention capacity leading to hot and dry skin.

In addition, some people show some behavioural changes such as confusion, disorientation, or staggering. 

"Avoid sudden temperature changes like shuttling betweeen a cool environment to an extremely hot one. Shut off the cooling to bring yourself down to the room's temperature before stepping out in the sun," suggested Abhi while listing out some dos and don'ts.

Avoid direct exposure to sunlight, especially during afternoons. And if that it unavoidable, one needs to cover the head.

Light-coloured cotton clothing should be preferred as these provide enough ventilation to the skin.

One also needs to be well hydrated to avoid dehydration. 

"Five to seven litres of water is a must during the day," Abhi stated.