Recommendations for diagnosis and treatment of onychomycosis during the COVID-19 pandemic.

Dear Editor,

Onychomycosis is the most common nail disorder seen in clinical practice with worldwide prevalence 10% and significant impact on quality of life. Prior to the COVID‐19 pandemic, clinical examination, dermoscopy, and mycological examination were recommended for all patients with suspected onychomycosis, followed by a discussion of appropriate treatment options. However, with prevalence of COVID‐19, non‐urgent in‐person visits are deferred, and telemedicine may be utilized to address some aspects of onychomycosis diagnosis and treatment. In this communication, we review the literature and suggest guidelines for onychomycosis management during the COVID‐19 pandemic.

Telemedicine may be appropriately utilized to assess patients with suspected onychomycosis, but is better optimized for patients with prior mycological confirmation. All 20 nails and web spaces are examined, as well as, both surfaces of digits, hands and feet in an area with excellent lighting. The video examination is best supplemented with photographs sent prior to the visit. Clinical findings suggestive of onychomycosis include onycholysis, subungual hyperkeratosis, and nail plate thickening/yellowing. Scale in the web spaces and/or plantar feet may be indicative of tinea pedis. Confirmatory testing is cost‐effective and fundamental to avoid treatment failures, misdiagnosis, and unnecessary side effects. Prior records of potassium hydroxide with direct microscopy, fungal culture, polymerase chain reaction, or clipping with histopathology are reviewed. A recent report demonstrating the presence of hyphae and/or fungal speciation is sufficient for discussion and initiation of treatment. For patients without prior sampling, treatment of onychodystrophy is deferred until in‐office confirmation is feasible; treatment of suspected tinea pedis can prevent worsening of onychomycosis in the interim.

Telemedicine may also be utilized for mycologically confirmed onychomycosis patients who have initiated treatment. It allows for accessible and quality care, and maintains connectivity between patients and dermatologists, while limiting COVID‐19 transmission. Adequate treatment adherence, proper application technique and assessment of adverse effects increase efficacy and safety of onychomycosis treatment. Older patients, in whom onychomycosis is prevalent, may experience technical difficulties embracing telemedicine due to visual or physical disabilities or technology. If video visits are not feasible, a telephone call with photographs can be used.

Since topical and systemic toenail onychomycosis regimens are 1 year and 12 weeks, respectively, we recommend follow‐up telemedicine visits every 3 months for topicals and 6 weeks for systemics. Since toenails grow approximately 1 mm/month, the degree of proximal clear nail can be measured at a 3‐month visit. The patient is also asked about adverse effects with proper application technique reviewed. Systemic therapies for onychomycosis are associated with a number of adverse events. In the United States, oral terbinafine and itraconazole are Food and Drug Administration‐approved for onychomycosis treatment, whereas fluconazole is used off‐label. The most common side effects of terbinafine are taste change/loss, pruritus or skin rashes, and less frequently, liver enzyme abnormalities. For itraconazole and fluconazole, drug‐drug interactions are more common adverse events, but liver enzyme abnormalities may also occur. Nonetheless, interval laboratory monitoring of liver enzymes in otherwise healthy adult or pediatric patients treated with oral antifungals is not recommended because of low incidence of hepatotoxicity, laboratory testing costs and patient discomfort. , , Most importantly, limiting laboratory monitoring may decrease patients' exposure to COVID‐19, which is of utmost important during the pandemic.

Onychomycosis treatment guidelines prior to the COVID‐19 pandemic are no longer applicable. Telemedicine can be used for initial consultation of patients with onychodystrophy and topicals prescribed for tinea pedis if indicated; patients with confirmed onychomycosis can be monitored for clear nail growth and side effects. Mycological confirmation and baseline blood work are deferred until COVID‐19 is less prevalent.

CONFLICT OF INTEREST

The authors declare no conflicts of interest.