Acute Mountain Sickness (AMS)
As you ascend to higher altitudes, the atmospheric pressure falls and the amount of oxygen available to you also reduces. Given adequate time the body will adapt to these changes - your heart beat, breathing and the amount of red blood cells that carry the oxygen around the body increases. Each individual will acclimatise at a different rate. Whether you have successfully trekked at higher altitudes before of not, you are advised to acclimatise properly coming up to 3000 meters. As a general rule you should not climb more than 500 meters a day when you head above 3000 meters - your level of fitness does not guarantee you will not be affected by high altitude.
It is advised that you do not take very young children above 3000 meters; they may not be able to covey or understand if being affected by AMS.
Symptoms of AMS
Initial:
Loss of appetite
Sleeplessness
Nausea – vomiting
Persistent headaches
Dizziness
Moderate:
Disorientation
Weakness
Slight swelling of face and hands
Breathlessness
Reduced urine output
Severe:
High altitude pulmonary oedema
High altitude cerebral edema