High Altitude Trekking Health Information


To explore more panoramic mountain views and escape from altitude problems all Himalayan Humanity trips have been carefully planned to allow for plenty of time for acclimatization. With the added benefit of lots of advice from experienced leaders, altitude problems are not something to worry about when choosing your trip. The following information is intended to give you an insight into the effects of altitude on the body and how these can best be accommodated. If you would like more detailed advice about your likely reaction to higher altitudes please do not hesitate to Contact Us.

Acute Mountain Sickness

Acute Mountain Sickness (AMS) is a group of symptoms usually appearing together, with variations among individuals. It appears in people who have recently arrived at high altitudes or have just gained altitude, and may start anywhere from a few hours to a few days after ascending. High altitude is commonly defined as altitudes greater than 3000 metres (10000 feet.)

Anyone trekking or climbing to, and in, high altitudes is at risk of developing AMS. Susceptibility varies from individuals and with the same person from time to time. Ascending quickly will increase its likelihood, and those who had it previously have a greater chance of getting it again. Physical conditioning has absolutely no influence on susceptibility. In fact, fit individuals tend to go faster and therefore may have a higher incidence. Overexertion and dehydration contribute to AMS and may be a predisposing factor. The key is to move at a slow, steady, comfortable pace, stay well hydrated and listen to your body.

The big concern here is dehydration, which can lead to rapid weakness and the inability. The following are the most common symptoms of AMS:

Headache is by far the most common single symptom. It can vary from a minor nuisance to a severe throbbing. The severity of the headache is a good guide to its significance. A minor headache can be from a hard day of exertion, sun, cold or dehydration. This will usually disappear with some fluids and rest. The morning upon waking, is a good time to judge symptoms. A headache upon awakening is probably due to altitude and should be taken more seriously. This may be accompanied by nausea or even vomiting. A headache may be noticed on a descent from a pass or summit. This is a delayed altitude effect and probably due to the exertion on ascending. Aspirin can be taken to help relieve the pain. As with all AMS symptoms, timely descent is the best course of action if symptoms persist.

Insomnia is the inability to sleep. Altitude insomnia is characterized by difficulty falling asleep and frequent wakening during the course of the night. It is most noticeable during the first week of the trip due to the foreign sleeping accommodations, jet lag, time change and other factors. This usually improves during the second week. Insomnia becomes a problem when lack of sleep interferes with daytime functioning. All sleeping medications, barbiturates and opiates should be used with caution at high altitudes. Dalmane, a mild sleeping medication, can be useful. Diamox, a diuretic, helps with the body's acclimatization process and can also be useful. Check with your doctor before acquiring and/or using such medication.

Gastrointestinal Symptoms. Rarely does a person with AMS have a good appetite at high altitude. The better the appetite at higher altitudes, the better a person is acclimatizing. Nausea is a problem, but will eventually pass as a person acclimatizes. Vomiting is a more serious problem. If not accompanied by other AMS symptoms, it is probably a 'stomach flu'. If it is in combination with diarrhea, fever or chills, it is usually dysentery, not AMS. The big concern here is dehydration, which can lead to rapid weakness and the inability for that person to continue. Continue to drink fluids, rehydration powders are helpful, and descend to lower elevations. To control nausea and vomiting in AMS, Compazine or Phenergan suppositories can be taken.

Pulmonary Symptoms. The cold, dry air of the mountains can cause a deep, hacking cough on exertion. Hard sweets/candies, throat lozenges and proper hydration usually help relieve this problem. A frequent cough in association with severe breathlessness on exertion or mild breathlessness at rest (compared to companions) could be an indication of high altitude pulmonary edema. Proper diagnosis, medication and descent are the course of action in this case.

Periodic Breathing. Irregular breathing is a common complaint above 3000 metres (10000 feet). It is the most noticeable at night, and characterized by four breaths or so, and then no breathing for as long as 10 or 15 seconds. This period of no breathing, apnea, will usually cause a person to waken in a panic. This symptom seems to be quite harmless and no cause for worry. It is caused by a change in the control of breathing within the brain. Diamox has been shown to improve this condition.

Lassitude is defined as weariness, indifference and/or fatigue. It differs from exhaustion which usually responds to 24 hours of rest. Lassitude progresses over 24 to 48 hours. A person may not get out of their tent for meals, talk with others or even refuse to drink sufficient fluids. This can lead to unconsciousness over the next 12 to 24 hours. It may occur without a headache, vomiting or shortness of breath. The person will usually exhibit a loss of coordination. Immediate descent is required!

Ataxia is a lack of coordination and balance that is very noticeable. Due to the lack of oxygen to the brain, this is a serious sign. Descent is necessary and oxygen if available. This condition can become serious 6 to 12 hours after it is diagnosed. Ataxia may also be seen in hypothermia. Rest and warmth are recommended after proper descent.

Reduced Urine Output. This is a difficult sign to evaluate. Proper fluid intake should be followed by regular, clear and copious urine output at high altitudes. Retention of fluids at high altitudes could be a sign of not acclimatizing properly, and should alert a person to be wary of AMS and other symptoms.

The above summary should by no means to be taken as a full and comprehensive explanation of Acute Mountain Sickness, but rather a brief discussion on the most common symptoms, and what a person needs to be aware of before and after arrival at high altitudes.

Reference Books

The following reference books provide a more thorough and complete discussion of Acute Mountain Sickness: