Sunburn and skin cancer are not the only negative potential consequences of excessive sun exposure. Strong sunshine is also normally associated with high environmental temperatures. This heat exposure makes it difficult for the body to maintain its correct core temperature.

The main techniques the human body has for losing heat are sweating and increasing blood flow to the skin. As sweat evaporates it absorbs heat, removing it from the surface and hence cooling the skin. Increasing blood flow to the surface of the skin enhances the flow of heat from the internal organs to the surface where it can then be lost through radiation, conduction, convection, and evaporation of sweat.


Increased sweat production naturally increases the body’s rate of loss of fluids, especially water. If this is not balanced by increased consumption of drinks and moist foods, then the body becomes dehydrated. Thirst is not a good indication of dehydration: your body is already significantly dehydrated before you begin to feel thirsty. Thirst sensation also reduces with age, especially over 50. Urine volume and colour is a better indication: a dark yellow colour and/or urinating less often than every 3–5 hours (or not at all) means that you are dehydrated.

It is therefore very important that you maintain your fluid levels in hot weather by consuming plenty of drinks – enough to maintain a healthy urine colour and frequency of urination. Water is best; alcohol is of no help and can lead to dehydration itself through upsetting the normal functioning of the kidneys and increasing water loss through urination.


If allowed to continue, dehydration can reduce the body’s ability to sweat. Humidity in the air also reduces the evaporation of sweat from the skin. Both conditions impair the body’s ability to cool itself and its core temperature rises, a condition known as hyperthermia (hypothermia is the opposite condition, reduction of core temperature).

In severe cases, the core temperature rises uncontrollably resulting in the symptoms of sunstroke (or heat stroke):

  • confused or hostile behaviour;
  • headaches;
  • reduced blood pressure leading to fainting or dizziness;
  • increased pulse and breathing rates;
  • an initial reddening of the skin, caused by increased blood flow as the body tries to cool itself, may be followed by a pale or bluish colour as a result of loss of blood pressure;
  • chills and symptoms of fever;
  • convulsions, especially in children;
  • nausea, vomiting and possibly temporary blindness.

If allowed to continue untreated, the organs of the body begin to fail, resulting in unconsciousness, coma and eventually death.


This is therefore a serious condition requiring emergency medical treatment: if any of these symptoms occur, seek help immediately. In the meantime, while waiting for assistance:

  • Move to a cooler area, such as indoors or at least into shade;
  • Remove clothing to promote heat loss – a fan can also help;
  • Bathe in cool water and/or apply cold compresses to the torso, head, neck and groin. Wrapping in wet towels or clothes can actually increase insulation and prevent cooling. Do not use ice or cold water as this can shut down the blood supply to the skin and dramatically impair cooling of the body.
  • Drink water – but not too much: a sudden large increase in fluid intake can overwhelm the body’s ability to deal with it, resulting in water intoxication, which can itself be fatal.

The best treatment, however, is prevention: don’t allow yourself to become even mildly dehydrated, by drinking enough to balance your losses through sweating, etc.

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