There has been much debate in recent years over the recommended rates of ascent climbers and trekkers should employ to minimise the risk of suffering from Acute Mountain Sickness (AMS) or its more serious forms High Altitude Pulmonary Oedema (HAPE) and High Altitude Cerebral Oedema (HACE).

Above 3000m (some say 2500m), current best practice advice for a healthy adult dictates no more than a 300m increase in sleeping altitude per day with a rest day every third day. This does not mean you can't ascend more than 300m in a day (eg. to cross a pass or attempt a summit), as long as you descend again before sleeping. Following this principle, an ascent of a 6000m peak starting at around 3000m should take 10 days. However in many cases (eg if there is limited amount of time or finance available) climbers will attempt such an ascent much more quickly, often leading to AMS, and preventing the ascent or worse.

Before planning your trip ask yourself whether a couple of extra days or "a few dollars more" are worth it to stay healthy and maximise your chances of success? It's also important to assess the ascent itinerary of any commercially organised trek before booking - are they compromising your safety by shaving days off an ascent? If you do plan an itinerary of rapid ascent, then it's highly recommended to attempt a lower/easier peak the week beforehand. This has the twin benefits of providing acclimatisation enabling your body to cope better with the rapid ascent to come, and allowing you to see how your body performs at altitude in a less serious situation.

Having said this at the risk of scare-mongering, let's not forget the flip side of the coin. Bear in mind that everyone acclimatises at different rates and has a different degree of susceptibility to AMS. Everybody can adapt to altitude given time, and it is up to the individual climber to ascend sensibly, based on their own previous experience and by "listening" to their body whilst climbing. Remember: there is no hard and fast rule - one climber may need to stick to the above "300m/day" rule, where another might operate on 500m/day or more - people can and do make rapid ascents of high peaks without incident. In the end it comes down to which end of the safety scale you want to work at, and your willingness to sacrifice time, money and even success for the sake of your health.

A note on Diamox (Acetazolamide)
Many climbers are aware of this drug, which can help in the prevention and relief of AMS. The important point to understand is that it only relieves the symptoms of AMS and will not prevent the condition worsening should a sufferer fail to descend or rest. Thus its indiscriminate use to allow continued or rapid ascent is extremely dangerous, possibly masking warning signs (symptoms) of HAPE and HACE and allowing ascent to a point where subsequent descent is difficult or impossible. Diamox should only be used for the relief of AMS in a controlled fashion, to allow descent and rest - the only cure for AMS. In short,

If you have symptoms - go no higher.  If symptoms persist - go down

Read the UIAA Mountain Medicine advice sheets for more details

More information:
The Mountain Traveller's Handbook by Paul Deegan
Altitude Illness - Prevention and Treatment by Stephen Bezruchka
Pocket First Aid and Wilderness Medicine by Jim Duff & Peter Gormly
Medicine for Mountaineers by James A Wilkerson

All the above books can be purchased from the BMC online shop
 

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