The prevalence of onychomycosis in the global population – A literature study

[[[ Background: ]]] Onychomycosis is a common disorder, and high prevalence figures are commonly cited in the literature. [[[ Objectives: ]]] Evaluate the prevalence of onychomycosis based on published studies. [[[ Methods: ]]] Relevant studies were identified in Medline by using specific search criteria. [[[ Results: ]]] Eleven population-based and 21 hospital-based studies were identified. The mean prevalence in Europe and North America was 4.3% [95% Confidence Interval (CI): 1.9-6.8] in the population-based studies, but it was 8.9% (95% CI: 4.3-13.6) for the hospital-based studies. Both population-based and hospital-based studies showed that onychomycosis is more common in toenails and is seen more frequently in males. The main causative agent was a dermatophyte in 65.0% (95% CI: 51.9-78.1) of the cases. Trichophyton rubrum was the single most common fungus and was cultured on average in 44.9% of the cases (95% CI: 33.8-56.0). Moulds were found on average in 13.3% (95% CI: 4.6-22.1) and yeasts in 21.1% (95% CI: 11.0-31.3). [[[ Limitations: ]]] We may not have been able to locate all studies. [[[ Conclusions: ]]] Onychomycosis is a common disorder, but it may not be as common as cited in the literature, because hospital-based studies might overestimate the prevalence of onychomycosis. It is more frequent in males, and toenails are more commonly affected. Dermatophytes, particularly T. rubrum, are the main causative agents.