Altitude Sickness Symptoms

Medical Author: Melissa Conrad Stoppler, MD
Medical Editor: Jay W. Marks, MD

People living at lower altitudes who enjoy a winter ski vacation may be at risk for acute altitude sickness (acute mountain sickness), the most common of the so-called altitude diseases. Doctors do not know exactly why altitude sicknesses occur, but it is believed that they result from changes in the body's responses to lowered levels of oxygen and air pressure changes.

Acute (sudden) altitude sicknesses can occur as low as 8000 feet (2500 meters), but the risk for altitude sickness increases with increasing altitude. Acute altitude sickness occurs in up to 50% of those living in the lowlands who ascend to a level of 14,000 feet (4200 m). Onset of the condition can begin any time from eight to 96 hours after arrival at altitudes over 8,000 feet. Individuals vary in their susceptibility to acute altitude sickness and may develop symptoms at different levels of altitude.

Headache is the most common symptom of acute altitude sickness, but affected persons may also experience:

• nausea,
• vomiting,
• fatigue, and
• sleep disturbances.

There are no specific tests available to diagnose acute altitude sickness; the diagnosis is made based upon the clinical symptoms and the history of travel to an unaccustomed elevation.

Some people are at greater risk for developing acute altitude sickness. Known risk factors include:

• a rapid ascent to high altitude;
• people with a prior history of altitude sickness;
• residence at an altitude less than 3,000 feet; and
• age less than 50 years

The best way to prevent acute altitude sickness is to ascend slowly (over a period of several days) to higher altitudes. Limiting physical activity for the first few days may also help. Acute altitude sickness is usually not a serious condition, and it resolves on its own with rest and over-the-counter analgesics for pain control. Maintaining adequate hydration may also help reduce the symptoms of acute altitude sickness. Two drugs, acetazolamide and dexamethasone (Decadron), have been shown to alleviate the symptoms of acute altitude sickness once they occur and are sometimes prescribed to help susceptible individuals acclimate to high altitude. If the condition becomes unusually severe, descent to a lower altitude is recommended.

Reference: Hackett PH; Roach RC. High-altitude illness. N Engl J Med 2001 Jul 12;345(2):107-14.