How do you prevent and treat blisters on a trek?

The short answer

Comfortable, well broken-in footwear is the single most important item on a trek. Boots should have a little extra room for socks, but not so much that your heel slips. A common mistake is buying boots that are too small, which causes blisters and black toenails on long downhills.

Wear a thin liner sock under a wool sock, change socks every day, and keep spare dry pairs in your day pack. At the first sign of a hot spot, stop and cover it with tape or a blister plaster before it becomes a blister. Light shoes for the evening let your feet rest. If a blister becomes red, hot, swollen or painful to walk on, ask your guide to help and see a medical post.