I know people may say "just don't over-exert an you won't need it," but I find that if the sun is a little brighter than I expected or my hiking partners are any faster than I am, I tend to sweat more or work harder (and also sweat more) than I would otherwise.

I find ibuprofen a giant help for joint pain, and it reduces swelling. NUUN Active Hydration Tablets (or powdered sports drink mix) are a great way to help with hydration, but I suppose maybe they don't count as "medication" exactly.