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Altitude Sickness

Topic Overview

What is altitude sickness?

Altitude sickness occurs when you cannot get enough oxygen from the air at high altitudes. This causes symptoms such as a headache, loss of appetite, and trouble sleeping. It happens most often when people who are not used to high altitudes go quickly from lower altitudes to 2500 m (8200 ft) or higher. For example, you may get a headache when you drive over a high mountain pass, hike to a high altitude, or arrive at a mountain resort.


Altitude sickness can be dangerous. It is smart to take special care if you go high-altitude hiking or camping (like in the Rockies) or have plans for a holiday or trek in high-altitude countries like Peru, Ecuador, or Nepal.

Altitude sickness is also called acute mountain sickness.

What causes altitude sickness?


What are the symptoms?

The symptoms of altitude sickness include:

  • Not feeling like eating.
  • Feeling sick to your stomach. You may vomit.
  • Waking up during the night and not sleeping well.
  • Feeling dizzy.


Altitude sickness can affect your lungs and brain. When this happens, symptoms include being confused, not being able to walk straight (ataxia), feeling faint, and having blue or grey lips or fingernails. When you breathe, you may hear a sound like a paper bag being crumpled. These symptoms mean the condition is severe. It may be deadly.


How is altitude sickness diagnosed?



How is it treated?



For the headache, you can take an over-the-counter medicine, such as ibuprofen (Advil, Motrin) or naproxen (Aleve). Do not give aspirin to anyone younger than 18. Aspirin has been linked to Reye syndrome, a serious illness. You may also use medicine to reduce feeling sick to your stomach or other symptoms.

A doctor can give you acetazolamide. This speeds up how fast your body gets used to the higher altitude. Nifedipine (Adalat XL) and dexamethasone are also used for altitude sickness. You may also be able to use oxygen or a specially designed pressure chamber to treat altitude sickness.

Go to a lower altitude if your symptoms are moderate to severe, they get worse, or medicine or oxygen treatment does not help. Go down at least 500 m (1600 ft). Go to a lower altitude as fast as you can or get emergency help if someone with you has severe symptoms such as being confused or not being able to walk straight. Go with the person. Never let someone with severe altitude sickness go down alone.

Can you prevent altitude sickness?


  • If you are going to altitudes higher than 2500 m (8200 ft), try to spend a night at a medium altitude before going higher. For example, in Canada, spend a night in Banff before going to the Rocky Mountains.
  • Sleep at an altitude that is lower than the altitude you were at during the day. For example, if you ski at 2900 m (9500 ft) during the day, sleep the night before and the night after at 2500 m (8200 ft). "Climb high, sleep low" is standard practice for those who spend time at high altitudes.
  • Studies show that starting to take ibuprofen 6 hours before climbing to high elevations and then taking it every 6 hours while climbing may help prevent altitude sickness.footnote 1, footnote 2 Ibuprofen may also reduce the symptoms of altitude sickness if you do get it.
  • You may consider taking acetazolamide or possibly dexamethasone before going to a high altitude.footnote 3 Talk to your doctor about this.

What if you have a lung problem or other disease?




  2. Pandit A, et al. (2014). Efficacy of NSAIDs for the prevention of acute mountain sickness: A systematic review and meta-analysis. Journal of Community Hospital Internal Medicine Perspectives, 4(4). Available online: Accessed May 21, 2016.


Current as of: August 22, 2019

Author: Healthwise Staff
Medical Review:
Anne C. Poinier MD - Internal Medicine
Kathleen Romito MD - Family Medicine
Adam Husney MD - Family Medicine
