Onychomycosis—fungal infection of the nail—is a common medical problem. Treatments are widely available, but relapse is common.
Onychomycosis is a common nail disorder caused by dermatophytes, non-dermatophytes, and yeasts and other molds. It is a disease more common in adults with a North American incidence of 3%-7% and may be rising.
Dermatophytes are the most common type of organism affecting the toe nail with 45% of the organisms being Trichophyton rubrum. Candida albicans is the most common organism causing infection in finger nails. Non-dermatophyte and yeast infections are uncommon in toenails.
The major clinical presentations include distal lateral subungual onychomycosis, white superficial onychomycosis, and proximal subungual onychomycosis. Other presentations include infections limited to the nail plate and sparing the nail bed and total dystrophic onychomycosis.
Risk factors include advanced age, swimming, tinea pedis, psoriasis, diabetes, cohabitation with others who are infected, and genetic predisposition.
Nail infections may be painful, may predispose to infections particularly in immunocompromised patients such people with diabetes. Newer treatments are expensive and not without risk, so it is important to accurately diagnose onychomycosis prior to treatment.
At the 2019 American Academy of Dermatology Annual Meeting in Washington, DC, Molly Hinshaw, MD, reported that up to 50% of diagnosed nail infections were in fact not nail infections and she stressed the importance of accurate diagnosis prior to treatment. Clinical diagnosis may suggest fungal infection, but laboratory evidence is necessary to confirm.
There are a number of nail lesions that mimic fungal infections including skin cancer, psoriasis, onychogryphosis, lichen planus, yellow nail syndrome, and other onychodytrophies. Sometimes these conditions coexist with onychomycosis. The diagnosis is clearly easy to miss on clinical grounds.
Several diagnostic tools are available, including:
Having made a diagnosis, the treatment decision will involve oral, topical, or mechanical therapy.
Oral: the oral therapies available to treat nail infection in the US, include Ketoconazole, Griseofulvin, Fluconazole, Itraconazole, and Terbinafine.
Topical treatment options include: Efinaconazole, Tavaborole, and Ciclopirox.
Mechanical treatment options:
In summary, onychomycosis is a common medical problem that may lead to coinfections and can be painful. Diagnosis prior to treatment is essential. Topical and oral treatments are widely available, but relapse is common. Newer agents are in the pipeline for use but is unclear if the FDA will approve for nail infection.