The Himalaya begins where other mountain ranges leave off. Everest Base Camp is at the foot of huge mountains, yet it is 1,000 meters higher than the highest point in Europe. Your body can adjust to these altitudes, but only if given enough time. Being in a hurry in the mountains of Nepal can be deadly! It also seems that excessive exertion at altitude (e.g. carrying a heavy pack) may predispose some people to altitude illness. So it may be advisable to carry a light pack and use a porter (they are not expensive).
Acclimatization's the word used to describe the adjustments your body makes as it ascends. You should adjust your schedule so that you average no more than 300 meters per day of ascent above 3,000 meters. If you fail to allow time for acclimatization, you may develop symptoms of AMS. The AMS may be mild enough to go away with a day's rest or if ignored may lead to death. All that is required to ensure a safe trek is basic awareness of AMS, and a willingness to rest or descend if you develop symptoms. As a result of the growing awareness of altitude problems there is only one death from AMS in Nepal out of every 30,000 trekkers. Even these deaths would be avoidable if everyone knew how to respond to AMS. There are no reliable figures for casualties among porters. Recognizing Acute Mountain Sickness
Acute Mountain Sickness (AMS) can develop at any altitude over 2,000 meters. The early symptoms are headache, extreme fatigue, and loss of appetite. Some people become breathless at rest. AMS is the result of fluid accumulating in parts of the body. Where it does not belong: in the brain, in the lungs or both. When mild symptoms develop, it is a signal that you must stay at that altitude until symptoms have gone away. Never ascend with any symptoms of AMS! Usually within one or two days you will feel well and can continue your trek.
If you are resting at the same altitude and your symptoms are becoming worse, then it is necessary to descend. Worsening symptoms of AMS include increasing tiredness, severe headache, vomiting and loss of coordination. There are signs of High Altitude Cerebral Edema of HACE. HACE can lead to unconsciousness and death within 12 hours if progressive symptoms are ignored. Increasing shortness of breath, cough and tiredness are signs of High Altitude Pulmonary Edema or HAPE. HAPE can also be rapidly fatal if ignored.
A person suffering from AMS may not have clear thinking and may have to be forced to descend. Even if someone is willing to descend they should never be allowed to descend alone. Keep descending until the person shows some sign of improvement, usually after 300-500 meters of descent. Even if the diagnosis is not clear, but might be AMS, you should descend. You can always re-ascend when the person feels better. It is best to start descending while the person who is ill can still walk. If the person can no longer walk, a yak or horse might be obtained. Porters can often be found to carry a sick person down. Do not wait for a helicopter. If you choose to administer oxygen or medications do not delay the descent to watch for improvement.
In summary, if you are not doing well at altitude, most likely you have some mild symptoms of AMS. Rest at the same altitude until you feel well. If you are getting worse at the same altitude, descend to at least the last point at which you test well. If you are not sure of the diagnosis, err on the side of being too cautious. Remember severe altitude sickness is entirely preventable if you follow these guidelines.

Prevention

1. Acclimatization- After a 1000m, ascent, stay one more night for acclimatization.
   
2. Do not make RAPID ASCENT, don’t go too fast too high.
   
3. No alcohol, sleeping pill and smoking
   
4. Drink more fluid 3 – 4 litters a day clean water boiled or treated/soup/juice, etc

Climb higher sleep lower

1. Over 3000m, 300m. Ascent a day.
   
2. Do not travel alone.
   

Treatment

Descent is the best Medicine; do not wait for the Helicopter

Medicine:

1. Oxygen
   
2. Diamox for AMS 125 mg. before dinner, for sleeping problems if feeling suffocated.
   
3. Nafedipine for HAPE
   
4. Steroids / Dexamethasone