Nail fungus (onychomycosis) is a chronic fungal infection of the fingernails and/or toenails and leads to slow destruction of the nail plate, as the fungus feeds on the keratin of the nail. The infection is progressive if left untreated and has no self-healing tendency (Tab. 1). The pathogens can vary depending on the climatic zones. In temperate climate zones – alongside Germany, other European countries and North America – the pathogens are predominantly dermatophytes. A nail fungus infection that is exclusively caused by dermatophytes is also called tinea unguium. In Germany, the most common dermatophyte causing nail fungus is Trichophyton rubrum. Candida onychomycosis is less common and onychomycosis caused by moulds is very rare. If yeast fungi (Candida spp.) are positively detected, secondary colonisation without significance as illness should always be considered. When yeasts are detected from fingernails, onychomycosis is more likely than when Candida species are cultured from toenail material. Moulds – also called "nondermatophyte moulds" (NDM) – occur more frequently in subtropical and tropical regions. Therefore, the pathogens will not be discussed further here.
Tab. 1. General guideline recommendation for therapy (according to Nenoff P et al. S1 guideline onychomycosis )
|The infection has no self-healing tendency and can become the starting point for further mycosis lesions of the skin and for bacterial complications, so it should be treated unless there are contraindications.|
Diagnosis – treatment of onychomycosis based on clinical picture and pathogen detection
Treatment of onychomycosis
The guideline defines the following therapeutic goals for the first time:
- Complete elimination of the pathogen as quickly and safely as possible, defined by a negative control examination (if possible using PCR method*).
*Fungal detection by means of PCR is reimbursable for privately insured persons according to the German Fee Schedule for Doctors. Those with statutory health insurance must pay for the service themselves.
- Clinically speaking, largely healthy nails (usually defined as <5–10% residual change at the distal nail edge).
- Prevention of further transmission or interruption of infection chains.
The most important therapeutic recommendations are listed in Table 2.
Tab. 2. Overview of guideline-based treatment (according to Nenoff P et al. S1 guideline on onychomycosis )
Local treatment with antifungal nail polish is recommended for mild or moderate nail infections (distal subungual onychomycosis, white superficial onychomycosis, max. 40% of the nail surface affected and/or max. 3 of 10 toenails affected).
Filing or roughening is recommended to reduce the diseased parts of the nail.
|Nail polish preparation||Application frequency|
|Amorolfine HCl 5% Acrylic nail polish (up to 80% nail surface)||1 x per week|
|Ciclopirox 8% acrylic nail polish||Every 2 days, from 2nd month 2 x per week|
|Ciclopirox 8% nail polish water-soluble + HP chitosan||1 x daily|
|Terbinafine (78.22 mg terbinafine/ml nail polish) water-soluble nail polish + HP chitosan||1 x daily for 4 weeks, then 1 x per week|
|Systemic treatment||For moderate and severe onychomycosis, it is recommended, provided there are no contraindications, to always treat orally (systemically). A combination antimycotic therapy (oral and topical) should be aspired to.|
250 mg 1 x daily
Toenails affected: 12 weeks
Only fingernails affected : 6 weeks
150 mg 1 x per week
for 3–6 months for onychomycosis of the fingernails and 6–12 months for toenail infection
400 mg daily (2 x 2 capsules à 100 mg per day [400 mg]) for 1 week, then three weeks’ break = 1 pulse.
Three pulses (1 week itraconazole + 3 weeks’ break) or 3 months for toenail infection.
For fingernail onychomycosis a shorter time, possibly only 2 pulses.
Once daily 200 mg (2 hard capsules) for 3 months, shorter if fingernail infection.
For Tinea unguium, 2 capsules à 50 mg (= 100 mg/d) daily for 12 weeks
Intermittent low-dose terbinafine therapy (off-label use, not supported by studies, „expert opinion“)
250 mg terbinafine daily for 3 days, then 250 mg once per week until clinical cure (up to 1 year)
Intermittent low-dose itraconazole therapy (off-label use, not supported by studies, „expert opinion“)
2 x 100 mg SUBA-itraconazole (2 x 2 capsules à 50 mg) for 3 days, then maintenance therapy once a week 2 x 100 mg SUBA-itraconazole (= 2 x 2 capsules à 50 mg) until clinical cure (up to 1 year)
|Selection of the antimycotic|
Trichophyton rubrum (most frequent causative agent)
Trichophyton interdigitale (second most frequent causative agent)
Topical: Amorolfine or ciclopirox nail polishes
Systemic: Terbinafine (T.rubrum + T.interdigitale), fluconazole (T.rubrum), itraconazole (T.rubrum + T.interdigitale)
Candida albicans and Candida parapsilosis (often on fingernails)
Topical: Amorolfine or ciclopirox nail polish
If necessary, additionally systemic: Fluconazole p.o. (continuous or interval therapy) or itraconazole, in the case of Candida parapsilosis terbinafine is also possible
Scopulariopsis brevicaulis (common)
Topical: Atraumatic nail removal with 40% urea paste. Amorolfine or ciclopiroxolamine nail polish, if necessary amphotericin B* (as suspension, *off-label use).
Often no response to systemic antifungal therapy; exception: Aspergillus spp., Onychocola canadensis (new: Arachnomyces nodosetosus): Terbinafine p.o. works in individual cases
|HP-Chitosan: Biopolymer Hydroxypropyl chitosan (HPCH); SUBA: Super-bioavailability-Polymer|
Onychomycosis in children
The most important therapeutic recommendations of the guideline on onychomycosis in children are summarised in Table 3.
Tab. 3. Guideline recommendation for local and systemic therapy in childhood (according to Nenoff P et al. S1 guideline onychomycosis)
|Local and systemic therapy in childhood|
Topical therapy is recommended for initial onychomycosis in childhood.
For advanced onychomycosis in childhood, systemic therapy is recommended.
|Terbinafine (off-label use)||Fluconazole (off-label use)||Itraconazole (off-Label use)|
62.5 mg/day for a bw of <20 kg or
125 mg/day for >20- 40 kg bw or
250 mg/day for >40 kg bw.
Continuous administration for 12 weeks.
|3-5 mg/kg bw (up to max. 50 mg/d) until healthy nail outgrowth|
5 mg/kg bw once daily. Capsules with the main meal, the solution one hour after the meal at the earliest on an empty stomach.
50 mg daily for bw <20 kg or 100 mg daily for >20 kg bw. Under 10 kg bw strictly body weight-adapted.
Intermittent low-dose therapy (not supported by studies; „Expert opinion“)
Terbinafine dosed according to body weight (see above) daily for 3 days, then one dose per week until clinical cure (up to 1 year).
Intermittent therapy 6 mg/kg bw once a week for 3–6 months for onychomycosis of the fingernails and 6–12 months for toenail infection.
Until clinical cure (up to 1 year).
Intermittent low-dose therapy (not supported by studies. Expert opinion)
Children 7–12 years 2 x 50 mg for 3 days (loading phase), then once a week 2 x 50 mg SUBA-itraconazole.
In children <7 years: 50 mg daily for 3 days (loading phase), then application once a week 50 mg. Until healthy nail growth.
Prophylaxis after treatment of onychomycosis
The complete guideline contents (register number 013 - 003) are available on the AWMF portal (https://www.awmf.org/leitlinien/detail/ll/013-003.html).
All information is given to the best of our knowledge and belief, but no liability is accepted in individual cases, especially for dosage recommendations, which must be checked individually and updated.
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- Gupta AK, Venkataraman M, Shear NH, et al. Onychomycosis in children – review on treatment and management strategies. J Dermatol Treatment 2022;33:1213–1224
- Nenoff P, et al. S1-Leitlinie Onychomykose (AWMF-Register-Nr. 013-003) (2022) available at: https://www.awmf.org/leitlinien/detail/ll/013-003.html
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Conflicts of interest: M. Niehaus is an employee of Almirall Hermal GmbH.
Disclosure: Publication funded by Almirall Hermal GmbH; P. Mayser receives a fee from Almirall Hermal for reviewing the contents.