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Altitude sickness

6-minute read

Key facts

  • Altitude sickness can happen if you travel to a high elevation — such as up a mountain.
  • It happens when your body has not had time to adjust to the lower amount of oxygen.
  • The main symptoms are a headache, cough, racing heart or trouble breathing.
  • Altitude sickness is a medical emergency.

What is altitude sickness?

Altitude sickness is also called mountain sickness. It can happen if you travel to a high elevation. When people talk about ‘altitude’ they mean how high a place is above sea-level.

You can’t get altitude sickness from climbing in Australia — as we don’t have very high mountains. In places like Nepal and South America, the mountains are very high. You may get altitude sickness in these places.

Altitude sickness can affect anybody. Even people who are young and very fit can get altitude sickness.

Getting symptoms of altitude sickness can depend on:

  • where you are — your height above sea level
  • the time it took you to get up to that height
  • if you usually have problems with your heart and lungs
  • if you have had altitude sickness before

Altitude sickness can happen very quickly. It can be fatal if it’s not treated.

What are the symptoms of altitude sickness?

If you have altitude sickness, you may feel dizzy and weak. You might also have a headache. Some people feel nauseous. It can feel like a hangover.

Altitude sickness can be worse at night. It can last for days, even if you stay at the same altitude.

If you have signs of altitude sickness affecting your lungs or brain, this is a medical emergency. You need help to come down the mountain as soon as possible. Breathing oxygen from a tank can help you.

CHECK YOUR SYMPTOMS — Use the Symptom Checker and find out if you need to seek medical help.

What causes altitude sickness?

Altitude sickness is caused by low oxygen levels in the air. This happens at altitudes above about 2,500 metres. It happens when your body has not had time to adjust to the lower amount of oxygen. Your body is not able to get enough oxygen to work properly.

When should I see my doctor?

See your doctor before travelling if you already have heart or lung health problems.

When on a mountain, watch for signs of a headache, cough, racing heart or trouble breathing. If this happens at high altitude, you need medical help immediately.

You should try and come down to a lower altitude as soon as possible.

FIND A HEALTH SERVICE — The Service Finder can help you find doctors, pharmacies, hospitals and other health services.

ASK YOUR DOCTOR — Preparing for an appointment? Use the Question Builder for general tips on what to ask your GP or specialist.

How is altitude sickness treated?

If you have altitude sickness, you should stay where you are or go down the mountain until your symptoms disappear.

You can treat your symptoms with rest, fluids and painkillers. It may take a few days to get better. You may also need treatment with and anti-nausea medicines.

It’s best not to drink alcohol. Do not take sedatives or sleeping pills. This is because they interfere with the way your body adapts to being at high altitude.

Can altitude sickness be prevented?

If you're planning to travel to a high altitude, it’s a good idea to first talk to your doctor. They can give you some medicines to help with adjusting to the high altitude. This is especially important if you have had altitude sickness before.

Some places at high altitude can be remote. It can be hard to get healthcare quickly. Make sure you know the symptoms of altitude sickness. People travelling with you should also know the symptoms.

If you start to have symptoms, do not climb higher. Take more time to let your body get used to the height.

You can try and avoid getting altitude sickness by:

  • Not climbing quickly from sea level to a great height. Do not go above about 2,500 metres for your first night's sleep.
  • Once you get above 3,000 metres, do not climb more than 500 metres a day.
  • Spending the night back down below the highest climb you have done that day.
  • Avoiding exercise at altitude.
  • Giving your body time to adjust to the lower oxygen levels.
  • Avoiding alcohol at high altitude.
  • Resting for 48 hours after arriving at a place of high altitude.

You have more chance of getting altitude sickness if you have a medical problem that affects your:

  • lungs
  • heart
  • blood

Complications of altitude sickness

In very bad cases, altitude sickness can cause:

  • high altitude pulmonary oedema (HAPE)
  • high altitude cerebral oedema (HACE)

These are medical emergencies.

High altitude pulmonary oedema (HAPE)

Altitude sickness can affect your lungs. This is called ‘high altitude pulmonary oedema’ or HAPE. People with HAPE can feel short of breath. You may also have a cough, a racing heart and your lips may turn blue.

In serious cases, HAPE can lead to lung swelling, severe breathlessness and death.

High altitude cerebral oedema (HACE)

Altitude sickness can cause your brain to swell up. This is due to fluid on the brain. This is sometimes called ‘high altitude cerebral oedema’ or HACE.

People with HACE can feel confused. You may be irritable or cranky and may not behave normally. HACE can lead to brain swelling, coma and death.

Resources and support

For more information about altitude sickness, you can call the healthdirect helpline on 1800 022 222 (known as NURSE-ON-CALL in Victoria). A registered nurse is available to speak with 24 hours a day, 7 days a week.

Learn more here about the development and quality assurance of healthdirect content.

Last reviewed: November 2023

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