Journal of Drugs in Dermatology:

Onychomycosis—a fungal infection of the nail bed or plate caused by dermatophytes, non-dermatophyte molds, or yeasts.

Treatment of onychomycosis is multifactorial and relies predominantly on the severity of nail disease and patient comorbidities.

Diagnosis:

For diagnosis of onychomycosis, look for one or more of the following clinical signs: onycholysis, subungual hyperkeratosis, nail plate thickening and crumbling, or nail discoloration. In the presence of one or more of these findings, especially if concomitant tinea pedis is found, confirmatory testing can aid in diagnosis.

Experts recommend confirming diagnosis via KOH microscopy, histopathology with PAS or Gomori methenamine silver staining, or fungal culture to rule out mimickers of onychomycosis prior to initiating treatment.

TAKE-HOME MESSAGE

Treatment:

Oral medications are generally efficacious, but there are safety concerns such as drug-drug interactions, smell/taste disturbances, allergic reactions, or possible liver toxicity.

Three oral medications are approved in the US for adults: terbinafine 250 mg once daily for 12 weeks, itraconazole 200 mg once daily for 12 weeks, and griseofulvin 375 mg once daily for 6+ months. Fluconazole, an off-label treatment in the US, is approved in other countries and can be used in certain situations.

Topical medications approved for adults include ciclopirox 8% lacquer, tavaborole 5% solution, and efinaconazole 10% solution, all of which are applied daily for 48 weeks.

The mycologic cure rate is highest with oral Terbinafine compared with topicals. Oral Terbinafine is preferred over topical therapy because of better effectiveness and shorter treatment duration.

Efinaconazole 10% topical solution has demonstrated the highest complete and mycologic cure rates.

For severe disease, oral Terbinafine is considered first-line. For mild to moderate disease, topical Efinaconazole or oral Terbinafine is recommended.

Treatment in special conditions:

Certain patient characteristics warrant alternative therapies:

·        Age >65, diabetic, peripheral vascular disease, or immunocompromised: topical therapy + oral terbinafine or oral fluconazole.

·        Liver or kidney disease: topical treatment

• An initial liver function test is recommended to identify undiagnosed disease in most patients. Interval monitoring may not be necessary in young or healthy individuals.
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·        Concomitant medications (check drug interactions): topical treatment ± oral terbinafine or oral fluconazole.

·        Concurrent nail psoriasis: treat onychomycosis first if clinically suspected.

• Pediatrics: topical efinaconazole and check entire family for infection.
• Pregnant or lactating: no specific recommendations.
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When primary treatment fails:

In the case of treatment failure, several suggestions are made by the authors. If terbinafine failure occurs, consider retesting to confirm initial diagnosis. Susceptibility testing (via mean inhibitory concentration, or MIC) can be done after 1 month off terbinafine treatment. If a low MIC is identified, repeat a second course of terbinafine plus a topical for maintenance. If a high MIC is identified, switch to oral fluconazole ± topical therapy. Switching to oral terbinafine should be considered if topical treatment fails; adjunctively, debridement of the affected nail(s) can be performed.

Ensure that patients understand that treatment can take 12 to 18 months and the affected nails may never fully return to their previous normal appearance.

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