Altitude Sickness

About Altitude Sickness

Altitude Sickness, often known as Acute Mountain Sickness (AMS), is a particularly important medical consideration while trekking in Nepal. Altitude Sickness means the effect of altitude on those who ascend too rapidly to elevations above 3,000 meters. Anyone may be affected by AMS regardless of strength or physical fitness. There are two types of Altitude Sickness, high altitude pulmonary edema (HAPE) and high altitude cerebral edema (HACE)

1.High-Altitude Cerebral Edema

When AMS becomes life-threatening, it is called high-altitude cerebral edema (HACE). HACE symptoms include vomiting, lethargy, confusion, drowsiness, loss of coordination and coma. The condition can become fatal after a few hours or a few days. Because the hallmark of HACE is the impairment of cognitive ability, a person with HACE may be too impaired to realize what is wrong with him and to properly evaluate his situation. According to, anyone behaving in an irrational or bizarre way should be suspected of suffering from HACE. 

2.High-Altitude Pulmonary Edema

AMS and HACE are the products of an oxygen-starved body. A different sort of high-altitude sickness is high-altitude pulmonary edema, or HAPE. This illness is the result of low air pressure causing a fluid build-up in the lungs. The condition can be fatal within just a few hours. HAPE is easily confused with AMS or HACE and it is possible for a person to suffer from HAPE and ACE/HACE at the same time. HAPE symptoms include lethargy, shortness of breath while resting or fast, shallow breathing, gurgling breaths, cough with a pink, frothy sputum, tightness or congestion of the chest, drowsiness and blue or gray lips and/or fingernails. 

The initial symptoms of AMS are as following:

Loss of appetite
Persistent headache
Dizziness, light heaviness, confusion, disorientation, drunken gait
Weakness, fatigue, lassitude, heavy legs
Slight swelling of hands and face
Breathlessness and breathing irregularity

Reduced urine output

These symptoms are to be taken very seriously. In case of the appearance of any of the above symptoms, any further ascent should be reconsidered. More serious problems can occur which can even cause death sometimes within a few hours. The main cure for the Altitude Sickness is to descend to lower elevations immediately. Acclimatization by ascending to no more than 300 to 500 meters per day above 3,000 meters and the proper amount of rest are the best methods for the prevention of AMS.

The literature and pamphlet published by the Himalayan Rescue Association (see Rescue Service below) consists of detailed information on AMS. The Central Immigration Office and all trekking agencies in Kathmandu distribute this pamphlet free of cost. Since these documents also give information on the list of suggested medical supplies for trekkers, it is a compulsory item for every trekker’s medical kit

Prevention of Acute Mountain Sickness.

Medications used to treat high altitude illness include:

Acetazolamide (Diamox)
Aspirin or acetaminophen for headache
Dexamethasone (Decadron)
Diuretics, such as Lasix
Oxygen: especially during sleep

The early use of acetazolamide can help prevent mountain sickness. Taking this medicine a day or two before, and for the first 2-3 days at altitude will prevent high altitude illness in most people. Oxygen promptly relieves headaches, dizziness, and most other symptom.