Acute Mountain Sickness (AMS)
AMS, commonly known as altitude sickness, is the cause of lesser quantities of oxygen in the air at 5500m/18,044 ft the air pressure is approximately half that of sea level, i.e. there is half the amount of oxygen (and nitrogen). For treks below an altitude of about 3000m/10,000 ft. altitude sickness is not normally a problem. However, it has the potential to affect all trekkers from 2500 m and above. AMS is caused by going up to higher altitude too fast. It can be fatal if all the warning signals are ignored. Note that it is not the actual altitude, but the speed at which you reach higher altitudes which causes the problem.
Altitude sickness is preventable by going to higher altitude slowly, giving your body enough time to adjust and drinking lots of water. Ultimately, it is up to you to recognize the symptoms, and only climb up if you are relatively symptom-free.
High Altitude Medical Advice for Travelers
Trekking in the Himalayas exposes people to high altitude for longer periods of time than in other places, and with this the risk of dying from altitudes sickness is higher in this region. Hence, it is very crucial to take the opportunity to acclimatize gradually.
Acclimatization is the process of human bodies having built-in adjustment mechanisms that can optimize performances at altitudes. If a person is transported suddenly to the top of Mt. Everest, he/she would lost consciousness in a few minutes, and most likely die due to acute hypoxia. However, the summit of Mt. Everest can be reached like many legends in the past, without using supplemental oxygen after getting acclimatized for many weeks.
Normal Symptoms at Altitude
- Every trekker will experience some or all of these, no matter how slowly they ascend:
- Periods of sleeplessness
- One needs more sleep than normal, often 10 hours or more.
- Occasional loss of appetite.
- Vivid, wild dreams at around 2500-3800m in altitude.
- Unexpected temporary shortness of breath (day and night).
- Periodic breathing that wakes you occasionally- consider taking Diamox.
- The need to rest/catch your breath frequently while trekking, especially above 4000m.
- Dried-up or blocked nose.
- HeadacheĂ˘€“ common among trekkers. Raising your head and shoulders while trying to sleep sometimes reduces the headache. If the headache continues, one could take a painkiller: aspirin (dispirin), paracetamol, Ibuprofen (Aduil) or acetaminophen (Tylenol). Never take sleeping tablets.
- NauseaĂ˘€“ can occur without other symptoms, but often nausea will develop with a bad headache. If you are better in the morning take a rest day, or if you still feel bad descend to a lower altitude.
- Lack of appetiteĂ˘€“ common at altitude due to too rapid ascending.
- Painful cough or a dry raspy cough.
Note: You only need to get one of the symptoms to be getting altitude sickness, not all of them.
Note that if one is having a headache from dehydration, ascending further is not dangerous. However, if it is due to AMS, the consequences can be fatal. One cannot tell the difference, so be cautious.