Health and Safety
You’ll likely encounter altitude sickness, known as soroche, at Cusco's 3,300-meter (10,825-foot) elevation. Drink lots of fluids, but eliminate or reduce alcohol consumption, and eat lightly as much as possible for the first day or two. Many hotels have an oxygen supply for their guests' use that can minimize the effects. The prescription drug acetazolamide can help. Check with your physician about it (allergies to the drug are not uncommon) and about traveling here if you have a heart condition or high blood pressure or are pregnant.
Warning: Sorojchi pills are a Bolivian-made altitude-sickness remedy whose advertising pictures a tourist vomiting at Machu Picchu. Its safety has not been documented, and it contains only pain relievers and caffeine, so it's best avoided.
Cusco is a fairly safe city, especially for its size, with a huge police presence on the streets, especially around tourist centers such as the Plaza de Armas, where you will see some specifically indicated as tourist police. Nonetheless, petty crime, such as pickpocketing, is not uncommon: use extra vigilance in crowded markets or when getting on and off buses and trains, and be sure to keep track of bags when stopping to eat.
Tap water is not safe to drink here. Stick with the bottled variety, con gas (carbonated) or sin gas (plain).