Sections View Full Chapter Figures Tables Videos Annotate Full Chapter Figures Tables Videos Supplementary Content + Download Section PDF Listen ++ For further information, see CMDT Part 6-55: Nail Disorders + Key Features Download Section PDF Listen +++ +++ Essentials of Diagnosis ++ A trichophyton infection of one or more fingernails or toenails Yellowish discoloration with heaping of keratin Separation of the nail bed +++ General Considerations ++ The species most commonly found is Trichophyton rubrum "Saprophytic" fungi may rarely (< 5%) cause onychomycosis Evidence supporting a genetic defect in the innate and adaptive immune system may explain why some people suffer from chronic tinea pedis and onychomycosis + Clinical Findings Download Section PDF Listen +++ +++ Symptoms and Signs ++ The nails are lusterless, brittle, and hypertrophic The substance of the nail is friable +++ Differential Diagnosis ++ Psoriasis Candidal onychomycosis Lichen planus Allergy to nail polish or nail glue + Diagnosis Download Section PDF Listen +++ ++ Laboratory diagnosis is mandatory since only 50% of dystrophic nails are due to dermatophytosis Portions of the nail should be cleared with 10% KOH and examined under the microscope for hyphae Fungi may also be cultured from debris collected from underneath the nailplate Periodic acid-Schiff stain of a histologic section of the nail plate will also readily demonstrate the fungus + Treatment Download Section PDF Listen +++ +++ Medications ++ Difficult to treat because of the long duration of therapy required and the frequency of recurrences Fingernails respond more readily than toenails For toenails, treatment is indicated for patients with discomfort, inability to exercise, diabetes mellitus, and immune compromise Topical therapy Limited value historically Evidence suggests that efinaconazole 10% performs better than other topical treatment options Tavaborole 5% solution is also approved, but its clearance rates do not appear to be as good as those of efinaconazole Ketoconazole is not recommended to treat any form of onychomycosis +++ Systemic therapy ++ Is generally required for the treatment of nail onychomycosis; fingernails can virtually always be cleared, whereas toenails can be cured 35–50% of the time and improved in about 75% of cases Fingernails Ultramicrosize griseofulvin, 250 mg three times daily orally for 6 months, is often effective Treatment alternatives, in order of preference, are terbinafine, 250 mg once daily orally for 6 weeks, itraconazole, 400 mg/day orally for 7 days each month for 2 months, and itraconazole, 200 mg/day orally for 2 months Off-label use of fluconazole, 400 mg once weekly for 6 months, can also be effective, but there is limited evidence for this option Toenails Terbinafine, 250 mg once daily orally for 12 weeks, is best treatment If terbinafine cannot be used, pulse oral itraconazole 200 mg twice daily for 1 week per month for 3 months is an inferior but acceptable alternative Griseofulvin is not effective + Outcome Download Section PDF Listen +++ +++ Follow-Up ++ Monitoring of liver enzymes and CBC is recommended monthly during terbinafine treatment Courses of terbinafine or itraconazole may need to be repeated 6 months after the first treatment cycle if fungal cultures of the nail are still positive +++ Prognosis ++ Once clear, fingernails often remain free of disease for years About 75% of patients will have substantial improvement with systemic therapy, and 35–50% will be mycologically and clinically cured at 1 year Relapses are more common with itraconazole than terbinafine in toenail onychomycosis +++ When to Refer ++ There is a question about the diagnosis Recommended therapy is ineffective Specialized treatment is necessary + References Download Section PDF Listen +++ + +Ghannoum M et al. Examining the importance of laboratory and diagnostic testing when treating and diagnosing onychomycosis. Int J Dermatol. 2018 Feb;57(2):131–8. [PubMed: 28653769] + +Iorizzo M. Tips to treat the 5 most common nail disorders: brittle nails, onycholysis, paronychia, psoriasis, onychomycosis. Dermatol Clin. 2015 Apr;33(2):175–83. [PubMed: 25828710] + +Kramer ON et al. Clinical presentation of terbinafine-induced severe liver injury and the value of laboratory monitoring: a critically appraised topic. Br J Dermatol. 2017 Nov;177(5):1279–84. [PubMed: 28762471] + +Kreijkamp-Kaspers S et al. Oral antifungal medication for toenail onychomycosis. Cochrane Database Syst Rev. 2017 Jul 14;7:CD010031. [PubMed: 28707751] + +Maddy AJ et al. What's new in nail disorders. Dermatol Clin. 2019 Apr;37(2):143–7. [PubMed: 30850036]