Welcome to Travelturtle, the travel health advice site that provides you with country specific medical and vaccination reports usually only available to registered UK healthcare professionals.
This page offers key advice on altitude sickness, prevention and treatment.
- Find specific information about what causes altitude sickness, and the ethos behind it.
- Source medical symptoms that are a clear indication of altitude sickness.
- Find information about those who are susceptible to it, and its hidden dangers.
- Find a comprehensive guide on how altitude sickness prevention and behavioural pattern that can limit the effects of altitude sickness on the body.
- Find key advice on altitude sickness treatment including any associated risks.
Staying at altitude (above 2000m)
Staying at altitude (above 2000m)
At high altitude there are fewer molecules of oxygen per breath, which can make travellers feel unwell. People typically begin to exhibit symptoms of acute mountain sickness, or altitude sickness, above 2,400m. It is often worse if they fly straight in without acclimatising (Mexico City and Aspen are around this height, while Quito and Bogotá are higher). Half of all travellers who fly in to altitudes above 3,500m – to places such as Cuzco, Leh and La Paz – will suffer marked symptoms.
Symptoms
- headache
- nausea and vomiting
- insomnia
- loss of appetite
- fatigue
- swelling of hands, face and feet
Who gets it?
- Those who ascend too fast.
- Those who have had it before, although this does not mean that they will always get it.
Like seasickness, some people are more sensitive than others to altitude. Fast ascent makes symptoms even more likely.
When is it dangerous?
- Altitude is dangerous for those who cannot tolerate a drop in oxygen levels, such as people with heart disease or COPD. They should be particularly aware of the risks and should take advice before travelling.
- At altitudes from 4,000 to 5,000m, around 2% of people will be affected by a severe form of altitude sickness, with the proportion increasing the higher the altitude.
- Pregnant women generally tolerate altitude well, but may need monitoring.
The severe forms are:
- pulmonary oedema – when fluid accumulates on the lungs causing breathlessness at rest, gurgling fluid in the lungs and white frothy phlegm
- cerebral oedema (more rare) – with progression to confusion, unsteadiness, lethargy and coma
Both cases necessitate immediate descent of at least 500m as a lifesaving measure.
Altitude sickness prevention
Sensible precautions and drugs can help to prevent altitude sickness. Travellers should:
- acclimatise – blood often becomes more alkaline in response to altitude (because of loss of CO2 due to hyperventilation), but kidneys will gradually correct for this. Also more red blood cells will be produced to carry oxygen to tissues
- climb high, sleep low – at night blood oxygen drops even at sea level, so at altitude people are much more vulnerable. Travellers should sleep as low as possible
- never go higher if they are ill with symptoms, as they may make themselves severely ill. Instead they should go down – they will quickly feel better.
- drink lots of fluid – at altitude water evaporates more easily, increasing the risk of dehydration
- not drink alcohol – it dehydrates and depresses breathing.
- Acetazolamide is not recommended for routine use in preventing altitude sickness.
Altitude sickness treatment
Acetazolamide is routinely used to treat AMS, usually at a dose of 250mg twice daily. Side effects include tingling in fingers, toes and lips, taste disturbance and increased urination. People allergic to sulpha medicines should not take acetazolamide.
Emergency treatment
Those going to particularly high altitude should take advice, but there are two emergency drugs for treating severe altitude sickness.
- For pulmonary oedema, nifedipine 20mg taken immediately and then repeated every 6 hours for a day.
- For cerebral oedema, dexamethasone 8mg initially, followed by 4mg at 6 hours and at 12 hours.
In both cases it is crucial to descend immediately, delay may be fatal.
Emergency non-drug treatments include treatment in a portable hyperbaric bag (Gamow bag) which simulates descent to a lower altitude, or treatment with oxygen.
Other potential risks
- Increased exposure to UV light at altitude, so good sun protection is vital.
- Coca tea is a traditional remedy for altitude sickness, but there is no evidence of effectiveness
- Boiling water to kill bugs may be less effective at altitude as water boils at a lower temperature than at sea level. It should be kept boiling for longer at high altitude.
