What causes ingrown nails?

Updated: Nov 06, 2020
  • Author: Amira M Elbendary, MBBCh, MSc; Chief Editor: William D James, MD  more...
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The following factors are implicated in the development of ingrown nails:

  • Trimming toenails improperly: Cutting the toenail rounded, V shape or too short will cause bulging of the soft tissue and the possibility to leave a nail spur that is difficult to remove, resulting in an inflammatory reaction with pressure necrosis. The proper way to trim the toenail is to cut it straight across beyond the nail bed. [5]

  • Poorly fitting shoes: The nail plate can be forced out of the nail groove by footwear that has a toe box that is too small for the forefoot. The constant pressure on the nail bed and nail groove results in breakage that starts an inflammatory process and eventually results in an ingrown nail.

  • Nail plate abnormality: Increased curvature of the nail plate, as in pincer nail, may develop into an ingrown nail. [5] Deformities that result from prior trauma or underlying bone pathology may predispose to ingrown nails.

  • Excessive sweating: It was noted that ingrown nails are common among teenagers and soldiers, in whom excessive sweating is present, which results in softening of the nail fold. With the participation in sports, nail spicules may develop and can easily pierce the adjacent softened nail fold.

  • Obesity causing deepening of the nail groove

  • Drugs (eg, antiviral therapy for HIV disease): Indinavir has been reported to have an association with an increased incidence of ingrown nails. [6] Cyclosporine, docetaxel, oral antifungals, and retinoids can cause excess nail fold granulation tissue and eventual ingrown nail development. [7, 8, 9]

  • Generalized joint hypermobility: Joint hypermobility through changes in foot biomechanics and gate affection increases medial midfoot pressure and loading during walking, and, as the first metatarsophalangeal joint bears the highest pressure, an ingrown toenail in the big toe may develop. [10]

  • Onychomycosis: This infection may result in brittle nails, which may form nail spicules and pierce the adjacent nail fold.

  • Heredity: Some people are genetically predisposed to inwardly curved nails, with distortion of one or both nail margins.

  • Pathological hallux interphalangeal angle (≥14.5): This was correlated with the development of ingrown hallux nail and may act as a predisposing factor. [11]

  • Paronychia with sporangium formation: This was reported to cause an ingrown nail. [12]

  • Hematopoietic stem cell transplantation: Children with hematopoietic stem cell transplantation have a higher incidence of ingrown nails and were found to have the aggressive forms, with more than 50% of patients having nail edge and bilateral great toe involvement, as well as recurrence in 37.5%. [13]

  • Nail consistency: Young male runners who have a hard nail consistency were found to have a higher incidence of ingrown nail. [14]

  • Diabetes: The prevalence of ingrown nails was found to be higher in diabetic patients, suggesting the role of diabetic vasculopathy in the development and evolution of ingrown nails. [15]

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