Ingrown toenails are one of the leading causes of foot pain for which people seek medical treatment.
An ingrown toenail occurs when one or both sides of the nail grow into the surrounding skin. As the nail grows, its edge presses into and can eventually pierce the skin along the nail's border. People of all ages and backgrounds can suffer from ingrown toenails, though severe cases are most often seen in young adults. Because they are subject to more pressure and trauma, the big toe on each foot is more likely than the others to develop an ingrown toenail. Ingrown toenails are almost always painful.