Risk of altitude sickness occurs when travelling to destinations of 2,500-3,500m (8,200-11,500 feet), although cases have been reported at lower altitudes 1,500-2,500m (5,000-8,200 feet).
Risk factors for altitude sickness include the altitude itself, the rate of ascent and sleeping altitude. Travellers are at a higher risk if they have rapid ascent without a period of acclimatisation.
- Travellers should avoid travelling directly into areas above 3,500m
- A few days at an altitude below 3,000m prior to ascending should help travellers to acclimatise
- When ascending above 3,000m, this should take place gradually with no more than a 300-500m increase in sleeping altitude per day, and a rest day every three days
- Acetazolamide may be used off-label for altitude sickness prevention, although pharmacological prophylaxis is not encouraged
- Symptoms of altitude sickness include headache, fatigue, loss of appetite, nausea and sleep disturbance; if symptoms develop travellers should avoid further ascent and descend if there is no improvement
- Symptoms of severe forms of altitude sickness must be treated as a medical emergency and immediate descent is required; such symptoms include high-altitude cerebral oedema (confusion, difficulty with balance and coordination) or high-altitude pulmonary oedema (shortness of breath at rest, cough and chest tightness)