Your friend is on target. Foot powder is key to protecting your feet and it keeps them feeling dry and comfy. If you are worried about the long term effects of powder in your boots, use Dr Scholls odor eaters. They not only keep your boots from getting funky, they will kill the smell of really funky boots in a day or two. A pair usually cost less than 6 bucks. At that price you have nothing to loose.
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If it ain't bleeding, it doesn't hurt.