Acclimatization: how to avoid the altitude sickness?

On reaching heights above 3000m (9842.52 ft), heart pounding and shortness of breath are a normal response to the lack of oxygen in the air. However, for some visitors these symptoms can deteriorate into a conditions known as Soroche (or acute mountain sickness) when you can start to experience headaches, loss of appetite, extreme tiredness, sleeplessness and often nausea. Symptoms usually develop within the first day or two at altitude. To prevent Soroche, try to take things easy as soon as you arrive. Don't plan any strenuous treks  like Inca Trail until you've acclimatized for a few days. Avoid alcohol, cigarettes and heavy food. Drinking mate de coca (an infusion of coca leaves) may help. It can be bought in any shop or order in a cafe. If symptoms become more severe and prolonged it is best to quickly seek medical attention and make arrangements to descend to a lower altitude. On recovery one can re-ascend slowly or in stages.

Many visitors use tablets to speed the acclimatization process and counter the symptoms of Soroche (Sorojchi-pills).

Cusco is located 3400m (11154.86 ft) above sea level so it is important that you plan your trip so that you can spend at least 2 days in Cusco prior to starting the trekking or long tours. This period will allow you to acclimatize.