Prophylaxis for mountain sickness is only worthwhile at heights above 4,000m and when ascent rates are above 500m/day, according to a systematic review.
The results showed that acetazolamide 750mg and dexamethasone 8-16mg are equally effective in preventing mountain sickness. Lower doses, including 500mg acetazolamide and 0.5 or 2mg dexamethasone, are not effective and should not be used, they say.
Data supporting the use of other drugs were sparse, say Dr Lionel Dumont (division of anaesthesiology, University of Geneva hospital, Switzerland) and colleagues. At low rates of ascent, prophylaxis showed no absolute benefit.
Mountain sickness is characterised by headache, loss of appetite, nausea, fatigue, dizziness and insomnia. Symptoms appear within three days of being at high altitude (British Medical Journal 2000;321:267).