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Recognizing Altitude Sickness

Symptoms of Acute Mountain Sickness (AMS)


Updated January 24, 2014

Altitude sickness, or acute mountain sickness (AMS), occurs at high altitudes. Moderate altitudes as low as 2000 meters (6562 feet) are high enough to create signs of altitude sickness in some people, especially those with certain medical problems. Symptoms usually come on within 72 hours of arriving at altitude. Visiters coming from sea level experience the most severe symptoms.

When visiting high altitude destinations, be aware of the most common symptoms:

  • headache
  • sleep disturbances
  • shortness of breath
  • loss of apetite or nausea
  • fatigue
When planning trips to destinations above 6500 feet, talk to your doctor about medications that may reduce symptoms. Acetazolamide may be taken before traveling to reduce onset of symptoms.

The best bet to reduce onset of altitude sickness is to ascend slowly to altitude. Unfortunately, flying to your destination prevents a gradual ascent. If you suffer any of the symptoms listed above after arriving at destination, seek medical treatment. Untreated, altitude sickness can lead to fluid in the lungs or pressure on the brain.

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Montgomery AB et al Effects of dexamethasone on the incidence of acute mountain sickness at two intermediate altitudes JAMA 1989 Feb 3; 261:734-736.

Montgomery AB et al Incidence of acute mountain sickness at intermediate altitude JAMA 1989 Feb 3; 261:732-734.

Chow T et al Ginkgo biloba and Acetazolamide Prophylaxis for Acute Mountain Sickness Arch Intern Med. 2005;165:296-301.

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