Official reprint from UpToDate®
www.uptodate.com ©2017 UpToDate, Inc. and/or its affiliates. All Rights Reserved.

Onychomycosis: Epidemiology, clinical features, and diagnosis

Adam O Goldstein, MD, MPH
Neal Bhatia, MD
Section Editors
Robert P Dellavalle, MD, PhD, MSPH
Moise L Levy, MD
Ted Rosen, MD
Deputy Editor
Abena O Ofori, MD


Onychomycosis refers to nail infections caused by fungi, including dermatophytes (tinea unguium), yeasts, and nondermatophyte molds. The major clinical presentations of onychomycosis are distal lateral subungual onychomycosis (picture 1A-B), white superficial onychomycosis (picture 2), and proximal subungual onychomycosis (picture 3A-C). Additional clinical manifestations are endonyx onychomycosis (infection limited to the nail plate and sparing the nail bed), total dystrophic onychomycosis (picture 4), and mixed pattern onychomycosis.

The epidemiology, clinical features, and diagnosis of onychomycosis will be reviewed here. The management of onychomycosis and the differential diagnosis of nail dystrophy are reviewed separately. (See "Onychomycosis: Management" and "Overview of nail disorders".)


Onychomycosis is a common disorder that is estimated to account for 50 to 60 percent of abnormal nails [1]. Population-based studies have found varied estimates of prevalence, ranging from less than 1 percent to 8 percent in Europe and the United States and less than 1 percent in central Africa [2]. A systematic review of population-based studies that assessed the prevalence of culture-proven dermatophyte, yeast, and nondermatophyte mold onychomycosis of the toenails found pooled prevalences of 3.22 percent (95% CI 3.07-3.38), 0.40 percent (95% CI 0.34-0.47), and 0.37 percent, (95% CI 0.32-0.43), respectively [3].

Onychomycosis is much more common in adults than in children. The systematic review found pooled prevalences of pediatric dermatophyte and yeast toenail onychomycosis of 0.14 percent (95% CI 0.11-0.18) and 0.09 percent (95% CI 0.06-0.13), respectively [3].

Onychomycosis occurs in both sexes. Most, but not all, studies have found higher prevalences in males than in females [2].

To continue reading this article, you must log in with your personal, hospital, or group practice subscription. For more information on subscription options, click below on the option that best describes you:

Subscribers log in here

Literature review current through: Nov 2017. | This topic last updated: Jun 26, 2017.
The content on the UpToDate website is not intended nor recommended as a substitute for medical advice, diagnosis, or treatment. Always seek the advice of your own physician or other qualified health care professional regarding any medical questions or conditions. The use of this website is governed by the UpToDate Terms of Use ©2017 UpToDate, Inc.
  1. Gupta AK, Jain HC, Lynde CW, et al. Prevalence and epidemiology of onychomycosis in patients visiting physicians' offices: a multicenter canadian survey of 15,000 patients. J Am Acad Dermatol 2000; 43:244.
  2. Sigurgeirsson B, Baran R. The prevalence of onychomycosis in the global population: a literature study. J Eur Acad Dermatol Venereol 2014; 28:1480.
  3. Gupta AK, Daigle D, Foley KA. The prevalence of culture-confirmed toenail onychomycosis in at-risk patient populations. J Eur Acad Dermatol Venereol 2015; 29:1039.
  4. Romano C, Gianni C, Difonzo EM. Retrospective study of onychomycosis in Italy: 1985-2000. Mycoses 2005; 48:42.
  5. Foster KW, Ghannoum MA, Elewski BE. Epidemiologic surveillance of cutaneous fungal infection in the United States from 1999 to 2002. J Am Acad Dermatol 2004; 50:748.
  6. Hay RJ, Baran R. Onychomycosis: a proposed revision of the clinical classification. J Am Acad Dermatol 2011; 65:1219.
  7. Sigurgeirsson B, Steingrímsson O. Risk factors associated with onychomycosis. J Eur Acad Dermatol Venereol 2004; 18:48.
  8. Piérard GE, Piérard-Franchimont C. The nail under fungal siege in patients with type II diabetes mellitus. Mycoses 2005; 48:339.
  9. Muñoz-Pérez MA, Rodriguez-Pichardo A, Camacho F, Colmenero MA. Dermatological findings correlated with CD4 lymphocyte counts in a prospective 3 year study of 1161 patients with human immunodeficiency virus disease predominantly acquired through intravenous drug abuse. Br J Dermatol 1998; 139:33.
  10. Zaias N, Tosti A, Rebell G, et al. Autosomal dominant pattern of distal subungual onychomycosis caused by Trichophyton rubrum. J Am Acad Dermatol 1996; 34:302.
  11. Faergemann J, Correia O, Nowicki R, Ro BI. Genetic predisposition--understanding underlying mechanisms of onychomycosis. J Eur Acad Dermatol Venereol 2005; 19 Suppl 1:17.
  12. Eyerich K, Foerster S, Rombold S, et al. Patients with chronic mucocutaneous candidiasis exhibit reduced production of Th17-associated cytokines IL-17 and IL-22. J Invest Dermatol 2008; 128:2640.
  13. Ploysangam T, Lucky AW. Childhood white superficial onychomycosis caused by Trichophyton rubrum: report of seven cases and review of the literature. J Am Acad Dermatol 1997; 36:29.
  14. Piraccini BM, Tosti A. White superficial onychomycosis: epidemiological, clinical, and pathological study of 79 patients. Arch Dermatol 2004; 140:696.
  15. Szepietowski JC, Reich A, Garlowska E, et al. Factors influencing coexistence of toenail onychomycosis with tinea pedis and other dermatomycoses: a survey of 2761 patients. Arch Dermatol 2006; 142:1279.
  16. Sigurgeirsson B. Prognostic factors for cure following treatment of onychomycosis. J Eur Acad Dermatol Venereol 2010; 24:679.
  17. Finch J, Arenas R, Baran R. Fungal melanonychia. J Am Acad Dermatol 2012; 66:830.
  18. Lubeck DP, Gause D, Schein JR, et al. A health-related quality of life measure for use in patients with onychomycosis: a validation study. Qual Life Res 1999; 8:121.
  19. Elewski BE. The effect of toenail onychomycosis on patient quality of life. Int J Dermatol 1997; 36:754.
  20. Drake LA, Patrick DL, Fleckman P, et al. The impact of onychomycosis on quality of life: development of an international onychomycosis-specific questionnaire to measure patient quality of life. J Am Acad Dermatol 1999; 41:189.
  21. Roujeau JC, Sigurgeirsson B, Korting HC, et al. Chronic dermatomycoses of the foot as risk factors for acute bacterial cellulitis of the leg: a case-control study. Dermatology 2004; 209:301.
  22. Bristow IR, Spruce MC. Fungal foot infection, cellulitis and diabetes: a review. Diabet Med 2009; 26:548.
  23. Lawry MA, Haneke E, Strobeck K, et al. Methods for diagnosing onychomycosis: a comparative study and review of the literature. Arch Dermatol 2000; 136:1112.
  24. Lilly KK, Koshnick RL, Grill JP, et al. Cost-effectiveness of diagnostic tests for toenail onychomycosis: a repeated-measure, single-blinded, cross-sectional evaluation of 7 diagnostic tests. J Am Acad Dermatol 2006; 55:620.
  25. Wilsmann-Theis D, Sareika F, Bieber T, et al. New reasons for histopathological nail-clipping examination in the diagnosis of onychomycosis. J Eur Acad Dermatol Venereol 2011; 25:235.
  26. Jung MY, Shim JH, Lee JH, et al. Comparison of diagnostic methods for onychomycosis, and proposal of a diagnostic algorithm. Clin Exp Dermatol 2015; 40:479.
  27. Lim CS, Lim SL. New contrast stain for the rapid diagnosis of onychomycosis. Arch Dermatol 2011; 147:981.
  28. Shemer A, Davidovici B, Grunwald MH, et al. New criteria for the laboratory diagnosis of nondermatophyte moulds in onychomycosis. Br J Dermatol 2009; 160:37.
  29. Gupta AK. Treatment of dermatophyte toenail onychomycosis in the United States. A pharmacoeconomic analysis. J Am Podiatr Med Assoc 2002; 92:272.
  30. Elewski BE, Leyden J, Rinaldi MG, Atillasoy E. Office practice-based confirmation of onychomycosis: a US nationwide prospective survey. Arch Intern Med 2002; 162:2133.
  31. Litz CE, Cavagnolo RZ. Polymerase chain reaction in the diagnosis of onychomycosis: a large, single-institute study. Br J Dermatol 2010; 163:511.
  32. Gupta AK, Zaman M, Singh J. Diagnosis of Trichophyton rubrum from onychomycotic nail samples using polymerase chain reaction and calcofluor white microscopy. J Am Podiatr Med Assoc 2008; 98:224.
  33. Weinberg JM, Koestenblatt EK, Tutrone WD, et al. Comparison of diagnostic methods in the evaluation of onychomycosis. J Am Acad Dermatol 2003; 49:193.
  34. Tsunemi Y, Takehara K, Miura Y, et al. Screening for tinea unguium by Dermatophyte Test Strip. Br J Dermatol 2014; 170:328.
  35. Pharaon M, Gari-Toussaint M, Khemis A, et al. Diagnosis and treatment monitoring of toenail onychomycosis by reflectance confocal microscopy: prospective cohort study in 58 patients. J Am Acad Dermatol 2014; 71:56.
  36. Cinotti E, Perrot JL, Labeille B, Cambazard F. Reflectance confocal microscopy for cutaneous infections and infestations. J Eur Acad Dermatol Venereol 2016; 30:754.
  37. Nath AK, Udayashankar C. Congenital onychogryphosis: Leaning Tower nail. Dermatol Online J 2011; 17:9.