The excitement, thrill and beauty of trekking in Nepal are directly proportional to elevation. Especially during the winter, travelling to snowy mountains at high altitudes is very common among both foreign and domestic tourists. Over 65,000 tourists arrived in 2016 with trekking as the purpose of their visit. There is, however, a darker side of trekking at higher altitudes which often goes ignored. This dangerous set of symptoms may claim the lives of hopeful adventurers. The culprit at hand is known as “Altitude Sickness”.

There are three types of altitude sickness: acute mountain sickness (AMS), high altitude pulmonary edema (HAPE) and high altitude cerebral edema (HACE). Among them acute mountain sickness is the most common and other two are complications of AMS. Altitude sickness is a negative health effect occurring at high altitudes due to the low levels of oxygen, and in some parts of the world, it is a common disease. In fact, acute mountain sickness affects 50 per cent of travellers in the Himalayas and 85 per cent in the Mt Everest region.

The main cause of altitude sickness is ascending faster than 500 metres per day. As altitude increases air pressure decreases, and the availability of oxygen to sustain mental and physical alertness also decreases. Dehydration can also be considered a cause of altitude sickness as trekkers experience a higher rate of loss of water vapour from the lungs.

Starting at about 2,400 metres, this disease grabs its victims like a bad hangover: people initially show signs of headache, nausea, and increased heart rate. The symptoms worsen if the trekker continues upwards. Eventually, they experience difficulty in breathing and vomiting. Some cases of altitude sickness are life threatening.  Seven-ten cases of fatality due to high altitude sickness occur annually in Nepal but all of these deaths are preventable.

By acclimatising the body to increasing altitudes, it is possible to prevent this disease.

Ascending slowly and taking plenty of rest along the way allows the body to adjust to lower oxygen levels and lower air pressure. In the case of altitude sickness, slow and steady wins the race.

If you are planning on going mountaineering or trekking, follow these additional steps to prevent altitude sickness. Take prophylaxis before your journey, test your red blood cells (RBC) before trekking as a low RBC count is directly associated with respiration complications, drink plenty of water to help your body acclimatise to higher altitudes and eat appropriately for the journey.