I agree with the posters above in both respects. Drink coca tea! Many times to CUZ and UIO and the elevation difference is critical for many people. UIO is much more manageable it is closer to the threshold trigger for soroche for many people but CUZ is well above. Also CUZ airport is at 3400m but much of Cuzco is located higher like the HGI. The extra 200 or 300m makes a big difference.

Also at such altitud dehydration is an issue but simply drinking more does not always work. The body adapts to lower partial O2 pressure by expelling water and the capacity to absorb h20 also diminishes. If I drink large volume of water at such altitud it exits almost immediately! More readily absorbed liquid forms are good for me actually eating foods with high water content like pasta is a way to counter this problem because absorption is slower and more constant during daily life.