Dehydration and Heat Related Illness

in Infants and Young Children


Our children’s bodies create a tremendous amount of heat. Normally, they’re cooled through sweating and by heat radiating through the skin.

But in very hot weather, high humidity, and other conditions, this natural cooling system may begin to fail, letting heat in the body build to dangerous levels. This can cause Dehydration and Heat Related Illness.

The most severe form of Heat Related Illness is Heat Stroke, a life-threatening medical emergency. In Heat Stroke, the body cannot regulate its own temperature. It can rise to 40°C or higher, leading to brain damage or even death if it isn’t quickly treated. Prompt medical treatment is required to bring the body temperature under control.


Causes of Dehydration and Heat Related Illness

A young child’s body surface area makes up a much greater proportion of his overall weight than an adult’s, which means young children in particular face a much greater risk of dehydration and heat-related illness.

Heat related Illness is caused by a child’s prolonged exposure to high temperatures, direct sun, and high humidity, without sufficient rest and fluids.

It can also happen when a child is left in, or becomes accidentally trapped in a car on a hot day. When the outside temperature is just above 30°C, the temperature inside a car can reach almost 50°C in just 20 minutes, quickly raising body temperature to dangerous levels.


Prevention of Dehydration and Heat Related Illness

Make sure that your child drinks cool water early and often. Only send your child out to play fully hydrated. Then, during play, make sure your child takes regular breaks to drink fluid, even if not thirsty.

Know that dehydration is cumulative. If your child is 1% or 2% dehydrated on Monday and doesn’t drink enough fluids that night, and it then gets 1% or 2% dehydrated again on Tuesday, it means that your child is 3% or 4% dehydrated at the end of the day.

A simple rule of thumb: if your child’s urine is dark in colour, rather than clear or light, it may be becoming dehydrated.

Make sure your child wears light-coloured, loose clothing in warm weather.

Don’t let your child engage in heavy activity outdoors during the hottest hours of the day.

Teach your child to come indoors immediately whenever it feels overheated or dizzy.


Symptoms of Dehydration and Heat Related Illness

Symptoms of Dehydration

Early signs of Dehydrations include fatigue, increased thirst, dry lips and tongue, lack of energy, and feeling overheated. But if the child waits to drink until it feels thirsty, he or she might already be dehydrated. Thirst doesn’t really kick in until a child has lost 2% of his or her body weight as sweat.

Untreated Dehydration can lead to worse types of Heat Related Illness, Heat Exhaustion and Heat Stroke.

Symptoms of Heat Exhaustion

  • increased thirst
  • weakness
  • fainting
  • muscle cramps
  • nausea and/or vomiting
  • irritability
  • headache
  • increase sweating
  • cool, clammy skin
  • elevation of body temperature, but less than 40°C

Symptoms of Heat Stroke

  • severe headache
  • weakness, dizziness
  • confusion
  • nausea
  • rapid breathing and heartbeat
  • loss of consciousness
  • seizure
  • no sweating
  • flushed, hot, dry skin
  • temperature of 40°C or higher


Treatment for Dehydration and Heat Related Illness

The first thing you should do with any Heat Related Illness is get the child out of the sun into a cool, comfortable place. Have the child start drinking plenty of cool fluids. The child should also take off any excess layers of clothing or bulky equipment. You can put cool, wet clothes on overheated skin.

Young children with Heat Exhaustion should be treated in the same way but should not be allowed back into the sun on the same day. If your child doesn’t improve, or can’t take fluids, see a doctor.

Heat Stroke is always an emergency and requires immediate medical attention. While you wait for the ambulance to arrive, have your child lie down and elevate his or her feet slightly for improved circulation. If your child is alert and coherent, give frequent sips of cool fluids such as water. However, if your child is vomiting, turn onto his or her side to prevent choking (Recovery Position).

Call for medical assistance immediately.