Whether you come Chivas or Arequipa (2300m), some of you will feel the lack of acclimatization and the difficulty to make efforts. For others, you will have the chance to enjoy a desert landscape ... breathtaking (just joking !). Local probably advise you to chew coca leaves to fight against the "soroce" mountain sickness. Personally, I have not really felt the effects nor needed (good), even crossing the pass at 4910 meters or 100 meters above Mont Blanc ... or maybe it is precisely thanks to active ingredients of the Coca ... well, to retest higher.