DefinitionAcute mountain sickness is an illness that can affect mountain climbers, hikers, skiers, or travelers at high altitude (typically above 8,000 feet or 2,400 meters).Alternative NamesHigh altitude cerebral edema; Altitude anoxia; Altitude sickness; Mountain sickness; High altitude pulmonary edemaCauses, incidence, and risk factorsAcute mountain sickness is brought on by the combination of reduced air pressure and lower oxygen concentration that occur at high altitudes. Symptoms can range from mild to life-threatening, and can affect the nervous system, lungs, muscles, and heart.In most cases the symptoms are mild. In severe cases fluid collects in the lungs (pulmonary edema) causing extreme shortness of breath. This further reduces how much oxygen enters the bloodstream and reaches