Moleskin is a layer of felt-like padding with an adhesive backing that can be put anywhere on your foot where your boots rub or chafe. Until your boots conform to your feet, use moleskin to keep that 'hot spot' from becoming a blister. Here is some good advice from Dr. Preston, Author of Wilderness First Aid . As you've discovered so painfully, the best treatment for blisters is prevention. And prevention begins with good fitting boots-no lift in the heel, snug over the instep, satisfying wiggle room in the toes.
Feet swell over the course of a day spent hiking, more so with a heavy pack.
Better to judge fit on a new pair of boots later in the day. And bring along your own sock combination-store socks never fit and who knows what you can catch from such grody things. Surgical supply stores sell it. Buy some individual packets of Betadine cleanser. If you develop a blister in the early stages, clean the area with the Betadine, and cover it with a piece of the Tegaderm.