DefinitionAn ingrown toenail occurs when the edge of the nail grows down and into the skin of the toe. There may be pain, redness, and swelling around the nail.Alternative NamesOnychocryptosis; Unguis incarnatus; Nail avlusion; Matrix excisionCauses, incidence, and risk factorsAn ingrown toenail can result from a number of things, but poorly fitting shoes and toenails that are not trimmed properly are the most common causes. The skin along the edge of a toenail may become red and infected. The great toe is usually affected, but any toenail can become ingrown.Ingrown toenails may occur when extra pressure is placed on your toe. Most commonly, this pressure is caused by shoes that are too tight or too loose. If you walk often or participate in athletics, a shoe that is even a little tight ca