Altitude sickness

Altitude sickness can happen when you're at a high altitude. It usually gets better in a few days with rest, but it can sometimes be life-threatening and need treatment.

Check if you're at risk of altitude sickness

You can get altitude sickness if you're in a place that is at a high altitude (usually more than 2,500 metres above sea level).

You're more likely to get it if you travel or climb to a high altitude quickly.

You can get it in places like:

You cannot get altitude sickness in the UK.

Symptoms of altitude sickness

Symptoms of altitude sickness usually start 6 to 10 hours after being at a high altitude.

The main symptoms include:

Sometimes, the symptoms can develop into more serious symptoms that can be life-threatening.

What to do if you get altitude sickness

If you're at a high altitude and have symptoms of altitude sickness or feel unwell:

Symptoms of altitude sickness usually get better in 1 to 3 days.

If your symptoms have gone and you feel better, you can travel or climb to a higher altitude.

Important: If your symptoms do not get better

If your symptoms get worse or do not improve after 1 day, go to a lower altitude if you can. Try to go around 300 to 1,000 metres lower.

Urgent advice: Get medical help immediately if:

You are at a high altitude and you or someone else:

  • have symptoms of altitude sickness and feel very unwell
  • are confused
  • have problems with balance or coordination
  • are seeing or hearing things that are not real (hallucinations)
  • feel short of breath, even when resting
  • have a cough or are coughing up frothy or bloody spit
  • have blue or grey skin, lips, tongue or nails (on brown or black skin this may be easier to see on the palms of the hands or the soles of the feet)
  • are very sleepy or difficult to wake

Go to a lower altitude straight away (around 300 to 1,000 metres lower) if you can.

Treatment for altitude sickness

Altitude sickness usually gets better without treatment if you rest.

You may be given medicine to help ease symptoms.

If your symptoms are more serious, you may be given:

Rarely, you may need to be treated with oxygen in a special air-tight chamber (hyperbaric chamber) to increase the level of oxygen in your blood.

How to reduce your risk of altitude sickness

There are some things you can do to help reduce your risk of getting altitude sickness.


  • travel or climb to a high altitude slowly to give your body time to get used to lower oxygen levels

  • spend a few days at an altitude below 2,500 metres before going any higher

  • have a rest day at the same altitude every 3 to 4 days (if you're at an altitude of 3,000 metres or more)

  • drink enough water so you do not get dehydrated

  • speak to a GP or travel clinic if you've had altitude sickness before or if you're travelling to a high altitude quickly – they may prescribe medicine to help prevent altitude sickness


  • try not to travel from an altitude that's less than 1,200 metres to an altitude that's more than 3,500 metres in 1 day

  • try not to fly directly to a place with a high altitude – if this is not possible, rest for 1 day before going any higher

  • try not to sleep more than 500 metres higher than you slept the night before (if you're at an altitude of 3,000 metres or more)

  • do not drink alcohol while travelling or climbing

Page last reviewed: 31 July 2023
Next review due: 31 July 2026