An ingrown toenail sounds like its name the nail juts into the nearby skin, causing pain and possibly leading to infection. A lot of things can factor into this painful condition, such as a family history of it or an injury to the toe. But the main causes are poorly trimmed toenails and ill-fitting shoes.”If you cut your nails too short or too deeply into the nail fold the tough skin that borders the nail, the skin can compress with shoe wear. Trimming nails so that they are curved at the edges rather than straight across invites the problem, as does wearing shoes that are too tight for toes to move around when you walk. Ignore an ingrown toenail too long and you might need surgery. So keep those nails where they belong on the outside of your tootsies, not within!