Symptoms of altitude sickness 

Symptoms of altitude sickness usually develop between 6 and 24 hours after ascending to high altitude.

Mild altitude sickness

Common symptoms of mild altitude sickness (sometimes called acute mountain sickness) can be similar to a bad hangover and may include:

  • headache
  • nausea and vomiting
  • dizziness
  • tiredness
  • loss of appetite
  • upset stomach
  • feeling unsteady
  • shortness of breath 
  • increased heart rate
  • difficulty sleeping
  • generally feeling unwell

The symptoms are usually worse at night.

Severe altitude sickness

Signs of severe altitude sickness can include:

  • worsening of the symptoms described above
  • a persistent, irritable cough
  • breathlessness (even when resting)
  • a bubbling sound in the chest
  • coughing up pink or white frothy liquid
  • clumsiness and difficulty walking
  • irrational behaviour
  • double vision 
  • fits (convulsions)
  • drowsiness
  • confusion

Severe symptoms could mean you're developing cerebral oedema or pulmonary oedema. These are potentially life-threatening complications of altitude sickness.

What to do if you have symptoms

If you have symptoms of mild altitude sickness, don't go any higher for 24 to 48 hours. If your symptoms don't improve or get worse during this time, you should descend immediately.

Severe altitude sickness is a medical emergency. Someone with severe symptoms should immediately descend to a low altitude and seek medical help.

Read more about treating altitude sickness.

Page last reviewed: 28/04/2015

Next review due: 28/04/2017