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The heat in our body is generated by the basal metabolic activity and lost by evaporation (through sweating), conduction, convection (through dilatation of blood vessels) and radiation. The center for controlling our body temperatures is in an area called hypothalamus in the brain. Our core temperature is maintained at 37 degree centigrade with a 0.5 degree variation on either side. Now the hypothalamus maintains the body temperature within this range. However environmental and other factors can alter our core temperature and cause various symptoms! In fact it could also be fatal!

Our core body temperature rises when there is too much heat generation. The body is not able to loose enough heat to compensate for the excessive heat which is being produced. It can be due to excessively high environmental temperature or when sweating is impaired. If you are suffering from any other illness or taking drugs like diuretics, you are more likely to suffer from these heat illnesses. Old age is yet another risk factor.

There is actually a spectrum of illnesses that can occur due to excessive heat. The first one is Heat Cramps. If you exercise vigorously in hot weather and sweat a lot, you will have heat cramps. These are painful muscle contractions which will go away with salt replacement. The good thing is that this condition doesn’t increase our core temperature and hence it is not dangerous! The next is Heat Syncope which is a common ill effect of heat. In this a person standing in the sun for too long becomes pale and collapses suddenly. This happens due to dilatation of blood vessels which results in low blood pressure. The brain doesn’t get enough blood supply and thus the person faints. It’s not a very serious condition and person gets back to normal within few minutes. The affected person should be made to lie down in the shade, with the head slightly down. This will increase the blood supply to the brain and the patient will recover quickly. Like heat cramps, this condition too doesn’t increase the core temperature.

Heat exhaustion is more severe than heat cramps and heat syncope. It typically occurs after several days of high temperature. The core (rectal) temperature rises, between 37 and 40 degrees centigrade. The affected person feels dizzy. They can also have profuse sweating, headache and weakness. The patient should be immediately removed from the heat source. Cool sponging and fluid replacement should be done immediately. Oral rehydration mixtures are given, however if the patient is unable to take orally then intravenous fluids can also be given. If this condition isn’t treated, it will lead to the most severe form of heat illness, Heat Stroke!

Heat stroke occurs when our core temperature exceeds 40 degree centigrade. It is basically the failure of the heat regulating mechanism in the brain. The skin becomes hot and dry. They patient can have vomiting, headache. They can also have convulsions which can lead to unconsciousness. This is a life threatening condition and can lead to shock, kidney and liver failure if not treated immediately. Cerebral and pulmonary edema can also occur. It can actually lead to multi-organ failure! The treatment consists of rapidly cooling the body in ice water bath. The core temperature should be monitored regularly. Fanning should be done to increase heat loss by convection. Cold crystalloid intravenous fluids are also given. Some patient may also need benzodiazepines for sedation. With correct treatment, most patients usually recover.

So next time you are standing in sun for too long, make sure you consume enough water and salt because too much heat can be really dangerous! It can actually kill you!