Ingrown Toenail



  • In an ingrown toenail, the distal margin of the nail plate grows into the lateral nail fold, causing irritation, inflammation, and sometimes bacterial or fungal infection:
    • Stage 1 (inflammation): erythema, edema, tenderness to palpation of lateral nail fold
    • Stage 2 (abscess): increased pain, erythema, and edema as well as drainage (purulent or serous)
    • Stage 3 (granulation): Chronic inflammation leads to further erythema, edema, and pain, often with granulation tissue growing over the nail plate and significant nail fold hypertrophy.
  • Can reoccur
  • Synonym(s): onychocryptosis, unguis incarnatus


  • Great toenail is most often affected.
  • Lateral edge of nail is more commonly affected than the medial edge.
  • Most common in males aged 14 to 25 years
  • Infrequent, but more often in elderly females than in elderly males
  • More common in those with lower incomes


  • 2.5% of total population
  • 5% of population aged > 65 years
  • 2:1 male to female ratio

Etiology and Pathophysiology

  • Nail plate penetrates the nail fold, causing a foreign body reaction (inflammation).
  • Bacteria or fungi may enter through the opening in the nail fold, causing infection and abscess formation.
  • The inflamed and infected area leads to granulation tissue and hypertrophy of the nail fold.

Risk Factors

  • Genetic factors
    • Increased nail fold width
    • Decreased nail thickness
    • Medial rotation of the toe
  • Many others proposed; none proven, including the following:
    • Distorted, thickened nail (onychogryphosis)
    • Fungal infection (onychomycosis)
    • Hyperhidrosis
    • Improper trimming of the lateral nail plate
    • Poorly fitting shoes
    • Trauma to nail or nail fold
    • Conditions that predispose to pedal edema (i.e., thyroid dysfunction, diabetes, obesity, heart failure, renal disease)

General Prevention

  • Properly fitting shoes
  • Proper nail trimming (see “Patient Education”)

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