This article needs more reliable medical references for verification or relies too heavily on primary sources. Please review the contents of the article and add the appropriate references if you can. Unsourced or poorly sourced material may be challenged and removed. Find sources: "Ingrown nail" – news · newspapers · books · scholar · JSTOR (January 2020)

Ingrown nail
Other names	Unguis incarnatus or Ingrown toenail[1]
An ingrown and infected toenail on the large toe of the right foot
Specialty	Orthopedics

An ingrown nail, also known as onychocryptosis, from Ancient Greek ὄνυξ (ónux), meaning "nail", and κρυπτός (kruptós), meaning "hidden", is a common form of nail disease. It is an often painful condition in which the nail grows so that it cuts into one or both sides of the paronychium or nail bed. While ingrown nails can occur in the nails of both the hands and the feet, they occur most commonly with the toenails (as opposed to fingernails).^{[citation needed]}

A common misconception is that the cause of an ingrown toenail is the nail growing into the paronychium, but it can also be caused by overgrown toe skin.^[2] The condition is caused by a microbial inflammation of the paronychium causing a granuloma within which the nail is buried.^[3] A true ingrown toenail is caused by actual penetration of flesh by a sliver of toenail.^[4]