Altitude sickness - Symptoms of altitude sickness
NHS Choices Medical Reference
Symptoms of altitude sickness usually develop between six and 24 hours of being at high altitude.
Symptoms of mild altitude sickness
Common symptoms of mild altitude sickness (sometimes called acute mountain sickness) can be similar to a bad hangover and may include:
- nausea and vomiting
- 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.
Symptoms of severe altitude sickness
Signs of severe altitude sickness can include:
- worsening of the symptoms described above
- a persistent, irritable cough
- breathlessness (even when resting)
- bubbling sound in the chest
- coughing up pink or white frothy liquid
- clumsiness and difficulty walking
- irrational behaviour
- double vision
- convulsions (fits)
Severe symptoms could mean you are 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, you should not go any higher for 24 to 48 hours. If your symptoms do not 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.