Heat-related illnesses

The main causes of illness and death during a heatwave are Respiratory and Cardiovascular diseases. Additionally, there are specific heat-related illnesses including:

  • Heat cramps – caused by dehydration and loss of electrolytes, often following exercise.
  • Heat rash – small, red, itchy papules.
  • Heat oedema – mainly in the ankles, due to vasodilation and retention of fluid.
  • Heat syncope – dizziness and fainting, due to dehydration, vasodilation, cardiovascular disease and certain medications.
  • Heat exhaustion – is more common. It occurs as a result of water or sodium depletion, with non-specific features of malaise, vomiting and circulatory collapse, and is present when the core temperature is between 37ºC and 40ºC. Left untreated, heat exhaustion may evolve into heatstroke.
  • Heatstroke – can become a point of no return whereby the body’s thermoregulation mechanism fails. This leads to a medical emergency, with symptoms of confusion; disorientation; convulsions; unconsciousness; hot dry skin; and core body temperature exceeding 40ºC for between 45 minutes and eight hours. It can result in cell death, organ failure, brain damage or death. Heatstroke can be either classical or exertional (e.g. in athletes).