Acute altitude sickness

Synonyms: Mountain sickness

Medical Specialties: Emergency medicine, Family practice, Internal medicine

Clinical Definition

Acute altitude sickness, also called mountain sickness, is a group of general symptoms triggered by traveling to a higher elevation, usually above 8,000 feet, too rapidly. The    potentially life-threatening illness is due to reduced air pressure and lower oxygen levels.

In Our Own Words

Altitude sickness, also known as mountain sickness, occurs when people ascend to higher elevations, often well above 4,000 feet, too rapidly. It’s usually mild in the case of high-altitude vacationers getting off the plane, but potentially life threatening in other scenarios.


As air pressure and oxygen levels become low, the nervous system, lungs, muscles and heart can all feel the impact. Common symptoms include fatigue, headache, nausea, shortness of breath and sleeping difficulty. More severe sickness can involve coughing up blood, confusion and blue skin color. Slower ascent is key to prevention. Treatment includes descent, and in severe cases, supplemental oxygen,  medications to help breathing and reduce brain swelling and replacement of fluids.  

Side Effects
  • Shortness of breath
  • Dizziness
  • Fatigue
  • Nausea
  • Coughing up blood
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