Natives of high altitude places (such as Peru) have larger hearts and lungs than the average person, as well as a higher red blood cell count. These adaptations allow them to cope with the lack of oxygen, caused by the altitude of their physical location. It is even proven that a person who relocates to a higher altitude will adapt to acquire these same physical conditions.
For us tourists, who are not naturally equipped to deal with such oxygen levels, there are some nasty side effects to deal with when visiting some of the worlds high altitude destinations, where we are at high risk of sickness from it. The symptoms of altitude sickness include shortness of breath, dizziness, exhaustion, headache, diarrhea, nausea and vomiting…all ingredients for a real enjoyable vacation, right?
Altitude affects every person differently, so it’s hard to know how to prepare for it. In America medicines for altitude sickness require a doctor’s prescription, in Peru it is an over-the-counter drug, and therefore not necessary to purchase until you arrive there. Advil and anti-diarrhetics are some other aides to keep in mind – and definitely something you’ll want in your pack if you’re doing high altitude trekking of any sort (better safe than sorry right?).
Ultimately though, it is best to take care when arriving in a high altitude location. Take it easy on your first day, eat something light (like soup), move slowly, and give your body rest. You might even take this into consideration when planning your trip, giving yourself an extra day in the beginning to acclimate. In Peru, coca leaf tea is usually offered immediately to tourists upon their arrival, as the leaf has many natural properties which help to add oxygen to the blood (relieving some of the effects of the altitude) – other parts of the world probably have their own specialized antidotes as well.