How can I prevent altitude sickness while trekking in the Peruvian Andes?

To prevent altitude sickness in the Andes, ascend gradually and stay hydrated, aiming for no more than 500 m (1,640 ft) increase per day above 2,500 m. Avoid alcohol and heavy meals the first 24‑48 hours, and consider taking acetazolamide after consulting a doctor. Spending a night at a lower elevation before tackling higher sites helps your body adjust.