Onchomycosis is a chronic fungal infection of the fingernails and toenails causing the nails to thicken, discolor, disfigure, and split. It commonly occurs after oncholysis and accounts for half of all nail disorders, affecting up to three percent of the population. Generally, most cases of onchomycosis are caused by dermatophytes, common fungi that causes skin, hair and nail infection. Although it affects both fingernails and toenails, it more commonly occurs in the toenails. In general, it may be difficult to treat, albeit curable, and reinfection is not uncommon. If left untreated, toenails can become very thick causing pressure and pain inside the shoes. Fingernail infections may lead to psychological and social troubles.

Subtypes of Onchomycosis

There are five subtypes of onchomycosis, which can occur individually but may also occur in combination. The following are the subtypes of onchomycosis:

  • Distal lateral subungual onchomycosis (DLSO or DSO) – occurs underneath the nail
  • White superficial onchomycosis (WSO) – occurs in the surface of the nail plate
  • Proximal subungual onchomycosis (PSO) – fungus invades the cuticle
  • Endonyx onchomycosis (EO) – fungus invades the nail plate
  • Candida onchomycosis – separation of nail from the nail bed

Causes of Onchomycosis

There are three main causes of onchomycosis, all of which produce a similar signs and symptoms, thus making it difficult to diagnose the primary cause.

  • Dermatophytes (90% of all cases) – Epidermophyton, Microsporum, Trichophyton species
  • Yeasts (8% of all cases) – Candida albicans
  • Nondermatophyte mols (2% of all cases)

Signs and Symptoms of Onchomycosis

Upon infection, signs and symptoms may not manifest instantaneously. Initial sign of onchomycosis is the thickening of the nail. The other signs and symptoms of onchomycosis include:

  • Nail discoloration, disfiguration and splitting
  • Pain, discomfort, irritation, and pressure, especially in toenails (severe cases)
  • May interfere with standing, walking, and exercising
  • Paresthesia
  • Self-esteem issues 
Onchomycosis may also cause self-esteem issus in an individual

Onchomycosis may also cause self-esteem issus in an individual

First Aid Management of Onchomycosis

Treatment for onchomycosis was difficult as medications were not effective. However, modern advances have given better option treatments to people inflicted with onchomycosis. Although treatments have significantly improved, it is expensive and the rate of recurrence remains high. In case of any signs and symptoms of infection in the nails, seek medical attention, as it is easier to treat at its earlier stages. Treatment for onchomycosis include the following:

Topical Antifungal Medications

  • Applied to the nail and skin to eliminate the fungi-causing disorder and other pathogens
  • Used only if half the nail is involved or patient cannot take oral medications
  • Amorolfine, sodium pyrithione, bifonazole/ urea, etc.

Oral Medications

  • Generally more effective as it can penetrate the nail plate
  • Terbinafine, itraconazole


  • Removal of the nail through surgery or use of chemicals

Laser Treatment

  •  Capable of penetrating nail tissue and disrupting fungal to kill them through laser therapy

Although onchomycosis is not generally considered a medical emergency, it is necessary to find early treatment for easier prognosis. To learn more about how to recognize signs and symptoms of infections such as onchomycosis, enroll in First Aid Courses.

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