- Author: Antonella Tosti, MD; Chief Editor: Dirk M Elston, MD more...
Onychomycosis is a fungal infection of the toenails or fingernails that may involve any component of the nail unit, including the matrix, bed, or plate. Onychomycosis can cause pain, discomfort, and disfigurement and may produce serious physical and occupational limitations, as well as reducing quality of life. See the image below.
Signs and symptoms
Patients with onychomycosis may present with the following:
Initially, complaints about the appearance of the nail, with no physical symptoms
As the disease progresses, interference with standing, walking, and exercising
Paresthesia, pain, discomfort, and loss of dexterity
Loss of self-esteem and inhibited social interaction
Onychomycosis has 5 main subtypes, as follows:
Distal lateral subungual onychomycosis (DLSO)
White superficial onychomycosis (WSO)
Proximal subungual onychomycosis (PSO)
Endonyx onychomycosis (EO)
Patients may have a combination of these subtypes. Total dystrophic onychomycosis, the most advanced form of any subtype, presents as a thickened, opaque, and yellow-brown nail. Presentation varies by subtype.
Features of DLSO are as follows:
Subungual hyperkeratosis and onycholysis, which is usually yellow-white in color
Yellow streaks and/or yellow onycholytic areas in the central portion of the nail plate
Features of WSO are as follows:
Confined to the toenails
Small, white, speckled or powdery patches on the surface of the nail plate
The nail becomes roughened and crumbles easily
Molds produce a deep variety of WSO characterized by a larger and deeper nail plate invasion
Features of PSO are as follows:
An area of leukonychia in the proximal nail plate that moves distally with nail growth
In PSO caused by molds, leukonychia is typically associated with marked periungual inflammation
Features of EO are as follows:
Milky white discoloration of the nail plate
No evidence of subungual hyperkeratosis or onycholysis
Features of candidal onychomycosis are as follows:
Develops in patients with chronic mucocutaneous candidiasis or immunodepression
Affects several or all digits
Total onychomycosis associated with periungual inflammation
The digits often take on a bulbous or drumstick appearance
See Clinical Presentation for more detail.
Direct microscopy of a 20% potassium hydroxide (KOH) preparation in dimethyl sulfoxide (DMSO) can screen for fungi. The technique is as follows:
Before obtaining a specimen, the nails must be clipped and cleansed with an alcohol swab to remove bacteria and debris
The preparation does not require heating or prolonged incubation if DMSO is a component of the KOH solution
In DLSO, obtain a specimen from the nail bed by curettage; the onycholytic nail plate should be removed, and the sample should be obtained at a site most proximal to the cuticle, where the concentration of hyphae is greatest
In PSO, the overlying nail plate must initially be pared with a No. 15 blade; then, a sample of the ventral nail plate may be taken
In WSO, a No. 15 blade may be used to remove a specimen from the nail surface
In suspected candidal onychomycosis, specimens should be taken from the affected nail bed closest to the proximal and lateral edges
Nail fragments must be small enough for examination under low power
Large pieces of nail plate may be pulverized prior to microscopy by using a hammer or a nail micronizer
Counterstains, such as chlorazol black E or Parker blue-black ink, may be used to accentuate the hyphae
Fungal culture can identify the species of organism and guide therapy. Culture techniques are as follows:
Two types of growth medium should be used, one for dermatophytes and one for nondermatophytes
Medium with cycloheximide (dermatophyte test medium [DTM], Mycosel, or Mycobiotic) selects for dermatophytes
Medium without cycloheximide (Sabouraud glucose agar, Littman oxgall medium, or inhibitory mold agar) isolates yeasts and nondermatophyte molds 
Cultures should be obtained from pulverized nail scrapings or clippings while the patient has abstained from antifungal medication for at least 2 weeks
The specimen should be kept at room temperature with the cap placed loosely over the inoculated medium
See Workup for more detail.
Medications for onychomycosis can be administered topically or orally. A combination of topical and systemic treatment increases the cure rate. Adjunctive surgical measures may also be used.
Topical therapy for onychomycosis is as follows:
Ciclopirox olamine 8% nail lacquer solution
Amorolfine or bifonazole/urea (available outside the United States)
Efinaconazole 10% topical solution (the first FDA-approved topical triazole for toenail onychomycosis)
Tavaborole 0.5% topical solution, an oxaborole solution (boron-containing compound)
Can be used in WSO and DLSO limited to the distal nail
Should be limited to cases involving less than half of the distal nail plate or for patients unable to tolerate systemic treatment
Topical treatments may be useful to prevent recurrence in patients cured with systemic agents
Oral therapy for onychomycosis is as follows:
Fluconazole and posaconazole  are off-label alternatives
Systemic treatment is always required in PSO and in DLSO involving the lunula region
Nonpharmacologic approaches include the following:
Mechanical, chemical, or surgical nail avulsion
Chemical removal with a 40-50% urea compound in patients with very thick nails
Removal of the nail plate as an adjunct to oral therapy
Onychomycosis (OM) refers to a fungal infection that affects the toenails or the fingernails. Onychomycosis may involve any component of the nail unit, including the nail matrix, nail bed, or nail plate. Onychomycosis is not life threatening, but it can cause pain, discomfort, and disfigurement and may produce serious physical and occupational limitations. Psychosocial and emotional effects resulting from onychomycosis are widespread and may have a significant impact on quality of life.
The main subtypes of onychomycosis are distal lateral subungual onychomycosis (DLSO), white superficial onychomycosis (WSO), proximal subungual onychomycosis (PSO), endonyx onychomycosis (EO), and candidal onychomycosis. Patients may have a combination of these subtypes. Total dystrophic onychomycosis refers to the most advanced form of any subtype.
Onychomycosis in patients who are immunocompromised is associated with increased severity and morbidity. Lesions may appear atypical and require more aggressive management compared with the healthy population. Proximal subungual (ie, proximal subungual onychomycosis) involvement is much more prevalent in patients with HIV infection than in those without HIV infection. In this population, white superficial onychomycosis is more commonly caused by T rubrum, rather than T mentagrophytes.
The diabetic foot may lead to serious complications associated with onychomycosis. Peripheral neuropathy and sensory loss may lead to increased trauma without pain in patients with diabetes. Bacterial colonization and vascular insufficiency may exacerbate the problem and may lead to serious sequelae.
Onychomycosis in elderly people is complicated by diseases (eg, poor vision, arthritis) that prevent optimal foot care. Nail changes are much more common in elderly persons and often involve the fingernails and the toenails. The potential for drug-drug interactions is more evident and must be addressed before initiating oral therapy.
The pathogenesis of onychomycosis depends on the clinical subtype. In distal lateral subungual onychomycosis, the most common form of onychomycosis, the fungus spreads from plantar skin and invades the nail bed via the hyponychium. Inflammation occurring in these areas of the nail apparatus causes the typical physical signs of distal lateral subungual onychomycosis. In contrast, white superficial onychomycosis is a rarer presentation caused by direct invasion of the surface of the nail plate. In proximal subungual onychomycosis, the least common subtype, fungi penetrate the nail matrix via the proximal nail fold and colonize the deep portion of proximal nail plate. Endonyx onychomycosis is a variant of distal lateral subungual onychomycosis in which the fungi infect the nail via the skin and directly invade the nail plate. Total dystrophic onychomycosis involves the entire nail unit (see the image below).
Nail invasion by Candida is not common because the yeast needs an altered immune response as a predisposing factor to be able to penetrate the nails. Despite the frequent isolation of Candida from the proximal nail fold or the subungual space of patients with chronic paronychia or onycholysis, in these patients Candida is only a secondary colonizer. In chronic mucocutaneous candidiasis, the yeast infects the nail plate and eventually the proximal and lateral nail folds.
The recent proliferation of fungal infections in the United States can be traced to the large immigration of dermatophytes, especially Trichophyton rubrum, from West Africa and Southeast Asia to North America and Europe.
The incidence of onychomycosis has been reported to be 2-13% in North America. A multicenter survey in Canada showed the prevalence of onychomycosis at 6.5%. Onychomycosis accounts for half of all nail disorders, and onychomycosis is the most common nail disease in adults. Toenails are much more likely to be infected than fingernails. Thirty percent of patients with a cutaneous fungal infection also have onychomycosis. The incidence of onychomycosis has been increasing, owing to such factors as diabetes, immunosuppression, and increasing age.
Studies in the United Kingdom, Spain, and Finland found prevalence rates of onychomycosis to be 3-8%.
Onychomycosis affects persons of all races.
Onychomycosis affects males more commonly than females. However, candidal infections are more common in women than in men.
Studies indicate that adults are 30 times more likely to have onychomycosis than children. Onychomycosis has been reported to occur in 2.6% of children younger than 18 years but as many as 90% of elderly people.
The goals for antifungal therapy are mycological cure and a normal looking nail. Mycological cure can be evaluated at the end of treatment, while clinical cure requires several more months owing to slow nail growth.
Clinical trials have repeatedly demonstrated higher efficacy for terbinafine compared with other antifungal treatments.[11, 12] A meta-analysis of 18 studies on terbinafine, 6 studies on pulse itraconazole, and 3 studies on fluconazole for onychomycosis showed a mycological cure rate of 76%, 63 %, and 48 % respectively.
Yellow streaks along the lateral margin of the nail and/or presence of yellow onycholytic areas in the central portion of the nail (dermatophytoma) are associated with a poor response to treatment.
Residual nail changes persist in most patients as a result of the frequent association of onychomycosis with traumatic toenail dystrophies.
Onychomycosis caused by molds, particularly Fusarium species, are often not responsive to systemic therapy.
Recurrence (relapse or reinfection) of onychomycosis is not uncommon, with reported rates ranging from 10-53%.
Fungal infections of the fingernails have a much more favorable prognosis than toenail infections.
Patients should be educated about the use of appropriate footwear, especially in high-exposure areas such as communal bathing facilities and health clubs.
Following treatment, patients must be advised that nails may not appear normal for up to 1 year, and prophylactic antifungal therapy may be required to prevent reinfection of the skin and the nails. Patients may use topical terbinafine cream twice daily for 1-2 weeks for early tinea pedis or a 1-week pulse of itraconazole (200 mg PO bid) at the first signs of onychomycosis.
Andre J, Achten G. Onychomycosis. Int J Dermatol. 1987 Oct. 26(8):481-90. [Medline].
Baran R, Hay RJ, Tosti A, Haneke E. A new classification of onychomycosis. Br J Dermatol. 1998 Oct. 139(4):567-71. [Medline].
Bohn M, Kraemer K. The dermatopharmacologic profile of ciclopirox 8% nail lacquer. J Am Podiatr Med Assoc. 2000 Nov-Dec. 90(10):491-4. [Medline].
Bristow IR, Spruce MC. Fungal foot infection, cellulitis and diabetes: a review. Diabet Med. 2009 May. 26(5):548-51. [Medline].
Lubeck DP. Measuring health-related quality of life in onychomycosis. J Am Acad Dermatol. 1998 May. 38(5 Pt 3):S64-8. [Medline].
Midgley G, Moore MK. Nail infections. Dermatol Clin. 1996 Jan. 14(1):41-49. [Medline].
Carney C, Tosti A, Daniel R, et al. A new classification system for grading the severity of onychomycosis: Onychomycosis Severity Index. Arch Dermatol. 2011 Nov. 147(11):1277-82. [Medline].
Cohen AD, Medvesovsky E, Shalev R, et al. An independent comparison of terbinafine and itraconazole in the treatment of toenail onychomycosis. J Dermatolog Treat. 2003 Dec. 14(4):237-42. [Medline].
Crawford F, Young P, Godfrey C, et al. Oral treatments for toenail onychomycosis: a systematic review. Arch Dermatol. 2002 Jun. 138(6):811-6. [Medline].
Iorizzo M, Piraccini BM, Tosti A. New fungal nail infections. Curr Opin Infect Dis. 2007 Apr. 20(2):142-5. [Medline].
Gupta AK, Scher RK, De Doncker P, Sauder DN, Shear NH. Onychomycosis. New therapies for an old disease. West J Med. 1996 Dec. 165(6):349-51. [Medline].
Jennings MB, Pollak R, Harkless LB, Kianifard F, Tavakkol A. Treatment of toenail onychomycosis with oral terbinafine plus aggressive debridement: IRON-CLAD, a large, randomized, open-label, multicenter trial. J Am Podiatr Med Assoc. 2006 Nov-Dec. 96(6):465-73. [Medline].
Katz HI, Gupta AK. Oral antifungal drug interactions. Dermatol Clin. 1997 Jul. 15(3):535-44. [Medline].
Kemna ME, Elewski BE. A U.S. epidemiologic survey of superficial fungal diseases. J Am Acad Dermatol. 1996 Oct. 35(4):539-42. [Medline].
Hull PR. Onychomycosis--treatment, relapse and re-infection. Dermatology. 1997. 194 Suppl 1:7-9. [Medline].
Cribier BJ, Paul C. Long-term efficacy of antifungals in toenail onychomycosis: a critical review. Br J Dermatol. 2001 Sep. 145(3):446-52. [Medline].
Ebihara M, Makimura K, Sato K, Abe S, Tsuboi R. Molecular detection of dermatophytes and nondermatophytes in onychomycosis by nested polymerase chain reaction based on 28S ribosomal RNA gene sequences. Br J Dermatol. 2009 Nov. 161(5):1038-44. [Medline].
Elewski B, Pollak R, Ashton S, Rich P, Schlessinger J, Tavakkol A. A randomized, placebo- and active-controlled, parallel-group, multicentre, investigator-blinded study of four treatment regimens of posaconazole in adults with toenail onychomycosis. Br J Dermatol. 2012 Feb. 166(2):389-98. [Medline].
Elewski BE. Clinical pearl: diagnosis of onychomycosis. J Am Acad Dermatol. 1995 Mar. 32(3):500-1. [Medline].
Elewski BE. Diagnostic techniques for confirming onychomycosis. J Am Acad Dermatol. 1996 Sep. 35(3 Pt 2):S6-9. [Medline].
Epstein E. How often does oral treatment of toenail onychomycosis produce a disease-free nail? An analysis of published data. Arch Dermatol. 1998 Dec. 134(12):1551-4. [Medline].
Evans EG. Causative pathogens in onychomycosis and the possibility of treatment resistance: a review. J Am Acad Dermatol. 1998 May. 38(5 Pt 3):S32-36. [Medline].
Faergemann J, Baran R. Epidemiology, clinical presentation and diagnosis of onychomycosis. Br J Dermatol. 2003 Sep. 149 Suppl 65:1-4. [Medline].
Friedlander SF, Chan YC, Chan YH, Eichenfield LF. Onychomycosis Does Not Always Require Systemic Treatment for Cure: A Trial Using Topical Therapy. Pediatr Dermatol. 2012 Dec 28. [Medline].
Manevitch Z, Lev D, Palhan M, Lewis A, Enk CD. Direct Antifungal Effect of Femtosecond Laser on Trichophyton rubrum Onychomycosis. Photochem Photobiol. 2009 Dec 7. [Medline].
Gupta AK, Drummond-Main C, Cooper EA, Brintnell W, Piraccini BM, Tosti A. Systematic review of nondermatophyte mold onychomycosis: diagnosis, clinical types, epidemiology, and treatment. J Am Acad Dermatol. 2012 Mar. 66(3):494-502. [Medline].
Gupta AK, Palese CS, Scher RK. How to treat special populations suffering from onychomycosis. Skin and Aging. 1999. 7:54-8.
Brooks M. FDA OKs first topical triazole antifungal for onychomycosis (Jublia). Medscape Medical News. June 10, 2014. [Full Text].
Valeant Pharmaceuticals International, Inc. Valeant Pharmaceuticals announces FDA approval of Jublia for the treatment of onychomycosis [press release]. Available at http://ir.valeant.com/investor-relations/news-releases/news-release-details/2014/Valeant-Pharmaceuticals-Announces-FDA-Approval-Of-Jublia-for-the-Treatment-of-Onychomycosis/default.aspx. Accessed: June 16, 2014.
Elewski BE, Rich P, Pollak R, Pariser DM, Watanabe S, Senda H, et al. Efinaconazole 10% solution in the treatment of toenail onychomycosis: Two phase III multicenter, randomized, double-blind studies. J Am Acad Dermatol. 2013 Apr. 68(4):600-8. [Medline].
Elewski B, Zane L, Rich P, Aly R, Gonzalez Soto R, Leon N. Pivotal phase III safety and efficacy results of tavaborole (AN2690), a novel boron-based molecule for the topical treatment of toenail onychomycosis. Presented at the American Academy of Dermatology 72nd Annual Meeting. March 21-25, 2014. Denver, Colorado.
Gupta AK, Ryder JE, Johnson AM. Cumulative meta-analysis of systemic antifungal agents for the treatment of onychomycosis. Br J Dermatol. 2004 Mar. 150(3):537-44. [Medline].
Gupta AK, Scher RK. Oral antifungal agents for onychomycosis. Lancet. 1998 Feb 21. 351(9102):541-2. [Medline].
Gupta AK, Scher RK, De Doncker P. Current management of onychomycosis. An overview. Dermatol Clin. 1997 Jan. 15(1):121-35. [Medline].
Gupta AK, Zaman M, Singh J. Fast and sensitive detection of Trichophyton rubrum DNA from the nail samples of patients with onychomycosis by a double-round polymerase chain reaction-based assay. Br J Dermatol. 2007 Oct. 157(4):698-703. [Medline].
Piraccini BM, Rech G, Tosti A. Photodynamic therapy of onychomycosis caused by Trichophyton rubrum. J Am Acad Dermatol. 2008 Nov. 59(5 Suppl):S75-6. [Medline].
[Guideline] Ameen M, Lear JT, Madan V, Mohd Mustapa MF, Richardson M. British Association of Dermatologists' guidelines for the management of onychomycosis 2014. Br J Dermatol. 2014 Nov. 171(5):937-58. [Medline].
[Guideline] American Academy of Dermatology. Ten Things Physicians and Patients Should Question. Choosing Wisely. Available at http://www.choosingwisely.org/societies/american-academy-of-dermatology/. October 29, 2013; Accessed: April 30, 2016.
Piraccini BM, Sisti A, Tosti A. Long-term follow-up of toenail onychomycosis caused by dermatophytes after successful treatment with systemic antifungal agents. J Am Acad Dermatol. 2010 Mar. 62(3):411-4. [Medline].
Piraccini BM, Tosti A. White superficial onychomycosis: epidemiological, clinical, and pathological study of 79 patients. Arch Dermatol. 2004 Jun. 140(6):696-701. [Medline].
Tosti A, Piraccini BM, Lorenzi S. Onychomycosis caused by nondermatophytic molds: clinical features and response to treatment of 59 cases. J Am Acad Dermatol. 2000 Feb. 42(2 Pt 1):217-24. [Medline].
Tosti A, Piraccini BM, Lorenzi S, Iorizzo M. Treatment of nondermatophyte mold and Candida onychomycosis. Dermatol Clin. 2003 Jul. 21(3):491-7, vii. [Medline].
Tosti A, Piraccini BM, Stinchi C, Colombo MD. Relapses of onychomycosis after successful treatment with systemic antifungals: a three-year follow-up. Dermatology. 1998. 197(2):162-6. [Medline].