The difficulty about mountain sickness is that it is unpredictable so it is difficult to give absolute guidelines. Children are sixteen times more likely to suffer from mountain sickness than adults and also it can be very difficult to diagnose warning symptoms in children under two years of age.

Children acclimatise quicker to altitude than adults but they are more susceptible and also succumb quicker when they do get into trouble. Anyone ascending with children must be aware of the dangers and know the kinds of symptoms that might indicate that the child is developing mountain sickness.

Dangerous altitude sickness is rare (even in adults) below an altitude of 2,500m/8,000ft. Sleeping high is riskier than walking over a pass. The only treatment is descent, so plan any trek to above 2,500m in such a way that a rapid descent of at least 500m is always possible. It is dangerous to venture high for a child with sickle cell trait or disease and for some children with cystic fibrosis; asthmatics should be at no increased risk although the cold and new trigger factors may precipitate an attack.

Travel to Tibet is probably unwise, whether you fly or drive in, it is not possible to acclimatise and a few foreign children have died from mountain sickness there. Similarly rapid ascents by road (e.g. Colorado) or rail (eg in Peru) or aeroplane (e.g. to La Paz, Mexico City or Ladakh) may be risky. Even the most experienced mountain doctors will find it tricky to identify early mountain sickness in children under the age of two; they become whingey, but its very difficult to reliably distinguish between unhappiness because of the cold, the cold, wind in the face, sheer boredom or fluid accumulating in the brain.

Anyone (and especially a child) who is off colour at an altitude of 8,000ft or above should be assumed to have mountain sickness seek medical attention as soon as possible, the treatment is to descend, mild symptoms may be relieved by rest and eating lightly. An unusual form of altitude sickness causes fluid to collect in the lungs. If anyone exhibits a cough that becomes wetter, with more difficult and faster breathing and heartbeat seek urgent medical assistance.