High Altitude sickness, also know as acute mountain sickness or altitude illness, arises when travelers are exposed to high altitudes. When ascending through the atmosphere e.g. by hiking up a mountain, the level of oxygen available decreases; thus the amount of oxygen contained in out bodies decreases. We have to breathe more deeply and quickly to obtain sufficient oxygen.

The body adjusts to the lack of oxygen (hypoxia) but when the body is taken above its comfort level symptoms of hypoxia distress may occur making you ill. Different people will suffer different AMS at different levels some symptoms may begin around 2000 meters above sea level or some may not appear to above this.

The average height at which symptoms begin to appear are about 2400 meters above sea level.
Common symptoms which may appear are headaches, fatigue, stomach sickness, dizziness and sleep disturbance. They will often arise 6-10 hours after ascent and generally subside in 1-2 days.
Tips to avoid altitude sickness are:

- If possible, don't fly or drive to high altitude. Start below 3,000 metres (10,000 feet) and walk up.
- Acclimatise to the altitude slowly!
- If you go above 3,000 metres (10,000 feet), only increase your altitude by 300 metres (1,000 feet) per day, and for every 900 metres (3,000 feet) of elevation gained, take a rest day to acclimatise.
- Climb high and sleep low! You can climb more than 300 metres (1,000 feet) in a day as long as you come back down and sleep at a lower altitude.
- If you begin to show symptoms of moderate altitude sickness, don't go higher until symptoms decrease.
- If symptoms increase, go down, down, down!
- Stay properly hydrated, at least four to six litres per day
- Eat a high calorie diet while at altitude.
- Avoid tobacco, alcohol and other depressant drugs including, barbiturates, tranquillisers, sleeping pills and opiates such as dihydrocodeine .
- Eat a high calorie diet while at altitude.