Altitude Sickness

Altitude sickness is an illness caused by the lack of oxygen in the air at high altitudes. It is sometimes called "high-altitude sickness."

What Is Altitude Sickness?

Altitude sickness is caused by a lack of oxygen. Altitude sickness can affect anyone at high altitude. The symptoms begin to appear at different elevations above sea level in different people. Altitude sickness usually is seen in mountain climbers, trekkers, skiers, and travelers to high-altitude areas. Factors that contribute to altitude sickness are the person's physical condition and fitness and the rate of ascent to a higher altitude. Altitude sickness usually starts to affect people at an elevation of 7,000 feet to 9,000 feet above sea level. However, some people experience the effects as low as 5,000 feet.

What Are the Symptoms of Altitude Sickness?

Altitude sickness usually appears within hours of reaching high altitude. Symptoms may include:

• headache
• irritability
• dizziness
• muscle aches
• fatigue or insomnia (difficulty sleeping)
• loss of appetite
• nausea or vomiting
• swelling of the face, hands, and feet.

More severe altitude sickness may cause swelling of the brain, which can lead to hallucinations, confusion, difficulty in walking, severe headaches, and extreme fatigue. Severe altitude sickness also may cause accumulation of fluid in the lungs, resulting in shortness of breath even while resting. Severe altitude sickness can be life threatening and must be treated immediately.

How Is Altitude Sickness Treated?

Diagnosis and treatment of mild altitude sickness generally is not necessary because the symptoms tend to subside within a day or two. Doctors sometimes recommend that people with altitude sickness take aspirin or ibuprofen to relieve the muscle aches. Mountain climbers sometimes take medication that prevents or treats many of the symptoms.

Severe altitude sickness is a serious and life-threatening medical condition that must be treated by a doctor with oxygen therapy and medicine to reduce brain swelling and fluid in the lungs. People with severe altitude sickness should be moved to a lower altitude to help lessen the symptoms.

Can Altitude Sickness Be Prevented?

The simplest way to avoid the symptoms of altitude sickness is to ascend to high altitude slowly. This allows the body a chance to become accustomed to the lower oxygen content of the air at high altitude. When people are planning to drive or to fly to a high-altitude location, it is important that they take it easy for the first few days and that they limit physical activity while the body is still getting used to the higher altitude.