Ingrown toenails are most likely to affect your big toe. They occur when the edges or corners of your toenail grow into the skin on the side of your nail. This causes pain, swelling, and ...

Medically reviewed by William Truswell, MD An ingrown toenail—medically known as onychocryptosis—refers to a toenail that has grown into your skin. The top corner of the nail grows into the flesh, ...