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What is hypothermia?

Hypothermia is a medical emergency. It occurs when a person's body temperature falls to below 35C (95F).

Always call 999 for an ambulance if you think someone has hypothermia.

What does hypothermia do to the body?

If your body temperature gets too low it stops your heart, nervous system and other organs from working normally.

Without help or treatment the heart and respiratory (breathing) system can fail - and a person can die.

Hypothermia symptoms

A person with hypothermia may not realise they have become too cold as the condition can lead to confusion, poor decision making and a lack of judgement.

Symptoms of mild hypothermia, with a 32-35C body temperature, include:

  • Cold skin
  • Shivering constantly
  • Feeling tired
  • Lacking energy
  • Skin looking paler
  • Rapid breathing, called hyperventilation.

Symptoms of moderate hypothermia, with a body temperature of 28-32C, include:

  • Shivering may stop
  • Not paying attention
  • Unable to think straight
  • Confusion
  • Lack of judgement
  • Problems moving
  • Lacking co-ordination
  • Feeling drowsy
  • Speech is slurred
  • Shallow and slow breathing, called hypoventilation.

Symptoms of severe hypothermia:

The symptoms of severe hypothermia with a body temperature below 28C, include:

  • Being unconscious
  • Very shallow breathing
  • Very weak or irregular pulse
  • Dilated pupils in the eyes.

A person with severe hypothermia may seem to be dead - not breathing and having no pulse - but these functions may just be too small to be noticeable. It is vital to get them to hospital where doctors can try to resuscitate them.

Hypothermia in babies

Although a baby with hypothermia can look healthy, symptoms include:

  • Cold skin
  • Limp
  • Quiet
  • Not feeding.


What causes hypothermia?

Cold conditions include wintry weather, icy winds making it feel even colder, and being cold and wet, such as being caught in the rain on a cold day.

Causes of hypothermia include:

  • Getting too cold outside during winter
  • Staying out in the cold too long so the body cannot generate enough heat, called exhaustion hypothermia
  • Not wrapping up warmly enough for the cold
  • Living in cold conditions so that heat is lost over a period of time, called chronic hypothermia
  • Falling into icy water - called acute hypothermia or immersion hypothermia
  • Young people getting too cold after a night out only in light clothes.


Who has a greater chance of developing hypothermia?

Anyone can get hypothermia if they are not protected from cold conditions, but some groups face a greater risk, including:

  • Babies, who are too young to regulate their body temperature and their bodies can lose heat very quickly in cold conditions
  • Older people
  • People taking medication that affects body temperature regulation or sedatives
  • People sleeping rough or homeless people
  • People abusing alcohol or drugs
  • People with dementia or Alzheimer's disease who may not realise their actions could lead to them getting too cold
  • People with heart disease, head injuries or circulation problems
  • Mountain climbers, ramblers and winter sports enthusiasts
  • People recovering from an operation in hospital, called perioperative hypothermia.


WebMD Medical Reference

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