Vinegar is dilute acetic acid, and acetic acid changes the pH of the skin surface. Fungi that cause athlete's foot and nail infection need a fairly narrow pH range to thrive; drop it and they struggle. That is the entire mechanism, and it is a good one — simple, cheap, and hard to get wrong.
Its second use is softening. The same acid that discourages fungus breaks down the keratin bonds in hard skin, which is why vinegar appears here for calluses and corns as well as infections. A vinegar soak before filing a callus does much of the work for you.
Apple cider vinegar and plain white vinegar both work. Apple cider is gentler and smells better; white is cheaper and slightly stronger.


