What is an ingrown toenail?

An ingrown toenail is a painful condition of the toe that occurs when the sides or corner of the toenail digs into the skin at the end or side of the toe. The disease mostly affects the outer edge of the big toe, although the nail on both sides of the toe, or nail on any toe can become ingrown.

An ingrown toenail is also known as onychocryptosis.

What causes ingrown toenails?

The causes for ingrown toenails are listed below, but the two most common reasons are ill-fitting shoes and improperly trimmed nails.

  • Ill-fitting shoes such as tight shoes, high heels and pointed-toe shoes cause the toes to be compressed together so that the nail curls into the skin and cannot grow normally.
  • Improper trimming of toenails can cause the nail edge or corner to dig into the skin. Toenails should be trimmed straight across so that the top of the nail should make a straight line.
  • Injury near the nail such as a ripped nail or nail peeled off at the edge can cause an ingrown toenail.
  • Fungal infections of the nail can cause a thickened or widened toenail to develop.
  • Prescribed medications, particularly oral retinoids such as isotretinoin and acitretin.
  • Abnormal nail shape, such as pincer or trumpet nails.

Information Source: DermNet NZ: https://dermnetnz.org/topics/ingrown-toenail/