Guideline sources The following summarized guidelines for the evaluation and management of onychomycosis are prepared by our editorial team based on guidelines from the German-Speaking Mycological Society (DMykG/DDG/BVDD/APD/DGKJ/DGHM/DGPI 2023), the Japanese Dermatological Association (JDA 2020), the British Association of Dermatologists (BAD 2014), and the American Association of Family Physicians (AAFP 2014). 1 2 3 4 Guidelines 1. Screening and diagnosis Diagnosis: confirm the diagnosis of onychomycosis with a test, such as potassium hydroxide preparation, culture, or periodic acid-Schiff stain, before initiating treatment. B https://web.pathway.md/diseases/rec3MbOi5lBwmI6OJ 1/6 6/30/23, 1:22 AM Onychomycosis Pathway 2. Diagnostic investigations History and physical examination: Elicit history, including underlying diseases (diabetes, circulatory disorders), disease course, risk factors (sports participation), and other disease cases in the surroundings. B Obtain integumentary assessment, especially to inspect the type of involvement and to assess for other clinical manifestations of dermatophytosis, such as tinea unguium in the fingernails, tinea pedum, and additional tinea corporis. B Direct microscopy: obtain direct microscopic examination for the diagnosis of onychomycosis. B Show 2 more Fungal culture: obtain fungal culture to detect the cause before instituting antifungal treatment. B Show 8 more Molecular testing: obtain molecular testing in addition to conventional fungal diagnostics with microscopy and culture. Consider obtaining molecular testing with PCR from dermatophyte deoxyRNA in the nail material as a supplementary detection method in combination with microscopic preparation and fungal culture B to aid in diagnosis and shorten the time to the start of targeted treatment. Show 2 more Resistance testing: Do not obtain routine resistance testing in patients with onychomycosis. D Suspect reduced sensitivity to terbinafine in case of onychomycosis not responding clinically to oral terbinafine treatment. B 3. Diagnostic procedures Histological examination: Obtain histological examination in patients with suspected fungal infection not confirmed by other methods or when such methods are not available. B Consider obtaining histological examination in combination with fungal staining (periodic acid- Shiff) or Grocott-Gomori staining in previously treated patients with negative mycological test results. Combine potassium hydroxide preparation and histology to increase diagnostic sensitivity. C 4. Medical management General principles: Take into consideration the following factors when deciding between topical and combined topical-systemic antifungal treatment: involvement of the nail matrix https://web.pathway.md/diseases/rec3MbOi5lBwmI6OJ 2/6 6/30/23, 1:22 AM Onychomycosis Pathway number of affected toenails or fingernails extent of the surface affected per nail patient multimorbidity drug interactions expected compliance. B Define the following goals in the treatment of onychomycosis: complete elimination of the pathogen as quickly and safely as possible, defined by negative repeat test (PCR method if possible) largely healthy nails clinically (defined usually as < 5-10% residual change at the distal nail margin) prevention of further spread and/or interruption of infection chains. Systemic antifungals: As per DDG 2023 guidelines, offer oral terbinafine (continuous treatment) in patients with moderate-to-severe onychomycosis. B Show 4 more As per JDA 2020 guidelines, offer terbinafine, itraconazole (pulse therapy), or fosravuconazole in patients with tinea unguium. A As per BAD 2014 guidelines, offer terbinafine (250 mg/day for 6 weeks in fingernail and 12-16 weeks in toenail infection) as first-line therapy in patients with dermatophyte onychomycosis. Obtain baseline LFTs and a CBC in adult patients with a history of hepatotoxicity or hematological abnormalities. B Show 5 more Topical antifungals: As per DDG 2023 guidelines, offer topical amorolfine (water-insoluble acrylic solution) or ciclopirox (water-insoluble acrylic or water-soluble solution) nail lacquers in patients with mild-to- moderate nail infections (distal subungual onychomycosis, white superficial onychomycosis, maximum 40% of the nail surface affected and/or maximum 3/10 toenails affected). B Show 2 more As per JDA 2020 guidelines, offer topical efinaconazole (10% solution) or luliconazole (5% solution) in patients with mild-to-moderate tinea unguium unable to take oral medications due to hepatic dysfunction or not wishing to take oral medications. B As per BAD 2014 guidelines, offer the following topical antifungals in patients with superficial and distal onychomycosis: Situation Guidance 5% lacquer once or twice weekly for 6-12 months Amorolfine 8% lacquer once daily for up to 48 weeks Ciclopirox https://web.pathway.md/diseases/rec3MbOi5lBwmI6OJ 3/6 6/30/23, 1:22 AM Onychomycosis Pathway 28% solution BID for 6-12 months. B Tioconazole Show 3 more 5. Therapeutic procedures Atraumatic nail removal: Perform atraumatic nail removal to reduce the fungally infected and hyperkeratotic nail material as an adjuvant measure before topical and systemic antifungal treatment in patients with onychomycosis. B Consider combining atraumatic nail removal with systemic antifungal treatment. C Laser and photodynamic therapies: Insufficient evidence to recommend photodynamic therapy in patients with onychomycosis. I Insufficient evidence to recommend near-infrared diode at 870 and 930 nm and millisecond 1064-nm Nd-YAG in patients with onychomycosis. I 6. Surgical interventions Surgical nail removal: As per DDG 2023 guidelines, do not perform traumatic (surgical) nail extraction in patients with onychomycosis. D As per BAD 2014 guidelines, do not perform surgical avulsion followed by topical antifungal therapy in patients with single-nail onychomycosis. Nail debridement: do not perform nail debridement alone as a treatment in patients with onychomycosis. Consider performing mechanical intervention to remove the dermatophytomas within the nail plate or bed. Nail drilling: consider performing drilling of the affected nails in patients with onychomycosis. C 7. Specific circumstances Pediatric patients: offer terbinafine (62.5 mg/day for < 20 kg weight, 125 mg/day for 20-40 kg weight, 250 mg/day for > 40 kg weight; for 6 weeks for fingernail infection and 12 weeks for toenail infection) as first-line therapy in pediatric (aged 1-12 years) patients with dermatophyte onychomycosis. Obtain baseline LFTs and CBC. A Show 3 more 8. Preventative measures https://web.pathway.md/diseases/rec3MbOi5lBwmI6OJ 4/6 6/30/23, 1:22 AM Onychomycosis Pathway Antifungal prophylaxis: consider offering long-term antifungal prophylaxis with amorolfine- or ciclopirox-containing nail lacquer preparations (applied less frequently than for treatment) after successful onychomycosis treatment. C Footwear disinfection: advise disinfecting footwear to prevent recurrence and decontaminate the environment. B 9. Follow-up and surveillance Follow-up: assess for clinical healing and obtain mycological testing to monitor treatment. E Show 2 more Clinical findings Patient demographics Symptoms Age > 60 Nail pain Past medical history Social history Chronic vein insufficiency Prolonged exposure to wet environments Diabetes mellitus Sports participation PAD Tight-fitting shoes Psoriasis Tinea capitis Microbiological findings Tinea corporis Tinea cruris Spores and hyphae on KOH wet mount Tinea manuum Tinea pedis Integument exam Brittle nails Hyperhidrosis Nail discoloration Nail thickening Onychodystrophy Onycholysis Subungual hyperkeratosis Yellow nail discoloration References https://web.pathway.md/diseases/rec3MbOi5lBwmI6OJ 5/6 6/30/23, 1:22 AM Onychomycosis Pathway 1. Pietro Nenoff, Dieter Reinel, Peter Mayser et al. S1 Guideline onychomycosis. J Dtsch Dermatol Ges. 2023 May 22. Online ahead of print. Open 2. Takashi Mochizuki, Ryoji Tsuboi, Ken Iozumi et al. Guidelines for the management of dermatomycosis 2019 . J Dermatol. 2020 Dec;47 12 1343 1373. Open 3. M Ameen, J T Lear, V Madan et al. British Association of Dermatologists' guidelines for the management of onychomycosis 2014. Br J Dermatol. 2014 Nov;171 5 937 58. Open 4. John W Ely, Sandra Rosenfeld, Mary Seabury Stone. Diagnosis and management of tinea infections. Am Fam Physician. 2014 Nov 15;90 10 702 10. Open https://web.pathway.md/diseases/rec3MbOi5lBwmI6OJ 6/6