Altitude illness is a condition which occurs in many travelers making rapid ascents to high altitudes. It is commonly referred to as acute mountain sickness (AMS). It most often occurs at altitudes of 3,000 meters (approximately 10,000 feet) or more. In some individuals, it has been reported as low as 2,500 meters (8,000 feet).
We suspect that altitude illness is caused by the body's reaction to lower levels of oxygen found at high altitudes. The disease may occur several hours to days after ascending to high altitudes. Symptoms range from mild to severe.
Classic, high risk areas of the world for altitude illness include any mountain range over 10,000 feet, such as the Alps, Andes, or Himalayas. In addition, travelers to areas of North American, East Africa, and the polar regions are at risk.
Altitude illness can range from mild to severe.
The last group of symptoms may represent fluid accumulation in the brain (high altitude cerebral edema) or lungs (high altitude pulmonary edema). In these severe cases, the disease can be fatal if not treated rapidly and requires descent to lower altitudes. Luckily, in most travelers, altitude illness is mild and does not become severe.
Asthma does not increase the risk of altitude illness. In fact, people with asthma often do well at altitude since there is less pollution in the air.
The best prevention is slow ascent. In general, ascent of altitudes of no more than 1,000 feet (300 meters) per day above 10,000 feet is recommended. Upon arrival at altitude, you should avoid strenuous activity until you fully acclimatize.
Maintain fluid intake to avoid dehydration and follow the maxim, "climb high and sleep low." Avoid alcohol, cigarettes and sedatives (including narcotics).
The active ingredient in coca leaves is a mild stimulant that may help you stay alert and hydrated. This may make you feel better at altitude. Unfortunately, it does not prevent altitude illness.
It is unknown whether these two medications are effective in preventing altitude sickness, and therefore, their use is not recommended.
Physical conditioning does not protect against altitude illness. Susceptibility is based on your body's response to altitude and is not reflective of aerobic capacity.
If slow ascent is not possible or if you have a history of recurrent altitude illness, preventive medications may be needed. An example is Mt. Kilimanjaro (19,340 feet), which is often climbed in less than seven days.
The drug of choice to prevent altitude illness is acetazolamide. Take this medication 24 hours before ascent above 10,000 feet through 24-48 hours after you reach peak altitude. Avoid this medication if you have a history of sulfa antibiotic allergy, liver or kidney disease, or severe lung disease. Acetazolamide may cause tingling of the lips, fingers and toes, frequent urination, and a metallic taste with carbonated beverages.
If you cannot take acetazolamide, dexamethasone can be used. If you've had adverse reactions to steroids or have diabetes, this drug may not be safe for you. Dexamethasone can cause headaches, nausea, dizziness, abdominal pain, and can suppress your immune function if used over a long period of time.
If symptoms of acute mountain sickness develop, you should stop your ascent, rest and get adequate fluids and calories. If altitude illness symptoms worsen, rapid descent to lower altitudes should begin as soon as possible. You should also see a medical professional.
Oxygen, use of hyperbaric chambers and medications may be needed.
Authored by: Hall Health Center Travel Clinic staff
Reviewed by: Hall Health Center Travel Clinic staff (AT), May 2014