Onychomycosis in Adults - Guideline for the Treatment of

Publication: 01/03/2008  --
Last review: 20/02/2017  
Next review: 01/02/2020  
Clinical Guideline
ID: 1389 
Approved By: Improving Antimicrobial Prescribing Group 
Copyright© Leeds Teaching Hospitals NHS Trust 2017  


This Clinical Guideline is intended for use by healthcare professionals within Leeds unless otherwise stated.
For healthcare professionals in other trusts, please ensure that you consult relevant local and national guidance.

Guideline for the Treatment of Onychomycosis in Adults.

Onychomycosis in Adults

Criteria for use of guidelines

  • Adult patients with onychomycosis

Investigations required

  • Toenail clippings (see “investigation” below)


  • To improve the diagnosis and management of onychomycosis in adults

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Clinical Diagnosis

Onychomycosis is the most common nail disease, affecting up to 40% of adults. Toenails are more commonly affected than fingernails. In the UK, up to 90% are caused by a dermatophyte, most commonly Trichophyton rubrum, and up to 5% by non-dermatophyte moulds. Toenail onychomycosis is often associated with tinea pedis.

The most common clinical presentation is that of distal-lateral onychomycosis, where the free nail edge becomes yellow and crumbly underneath. Superficial white onychomycosis is usually caused by Trichophyton mentagrophytes. Proximal subungual onychomycosis, where the infection starts from the proximal nail fold and involvement of many toe- and fingernails are more common in the context of immunosuppression. Investigation of diabetes mellitus and HIV may be indicated. All the different forms of onychomycosis can terminate in total dystrophic onychomycosis, where the entire nail is crumbly and the nail-bed as well as -matrix are involved.

The differential diagnoses of onychomycosis include psoriasis, onychogryphosis, chronic repetitive trauma and less frequently lichen planus and malignancies such as squamous cell carcinoma and malignant melanoma.

Onychomycosis is much more than just a cosmetic concern. A thickened nail plate can cause pain when wearing shoes and walking.  A fungal nail is a reservoir for fungal infection of the skin, including the groins, not just of the patient, but also the rest of the household. Around the infected nail, there is often infected skin providing a port of entry to bacterial infection such as cellulitis. Fungal spores can give rise to sensitization in predisposed individuals, worsening asthma, eczema or urticaria.

If onychomycosis is suspected, this should be confirmed mycologically, for which more than one sample may be required. Repeatedly negative mycology will eliminate the diagnosis of fungal nail disease and point towards another diagnosis.  When mycology is positive, the correct drug can be selected depending on the organism grown.  In patients not responding to standard courses of treatment including toenail infections with Trichophyton rubrum, combined treatment or additional physical reduction of the fungal reservoir can be planned. Onychomycosis caused by non-dermatophyte moulds does not respond well to oral antifungal therapy, and current effective management options are limited.

In patients who have not responded to initial treatment, an additional 3 months of oral terbinafine or a change to itraconazole is advised. Failing that, referral to dermatology should be considered, as well as in patients with non-dermatophyte moulds, in patients with co-existing non-fungal nail disease or with systemic disease limiting treatment options. Antifungal drug resistance is rare.

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Evidence level C1

  • Samples should be taken from any discoloured, dystrophic or brittle parts of the nail.  The affected nail should be cut as far back as possible through the entire thickness. The sample should include nail and crumbly material.
  • In suspected superficial white onychomycosis, a sample may be collected using a curette.
  • Specimens should be collected into a Dermapak or similar black card packet. If these are not available, then a sterile plain plastic universal container may be used.
  • As much material should be included as possible, to maximise the diagnostic yield.
  • If associated skin lesions are present, samples from these are likely to be infected with the same organism.
  • Laboratory diagnosis consists of microscopy to visualize fungal elements in the nail sample and culture to identify the species concerned.

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  • First-line for dermatophyte onychomycosis: oral Terbinafine electronic Medicines Compendium information on Terbinafine 250mg daily for 6 weeks for fingernails and 3-4 months for toenails. Review 3-6 months after initiation of treatment and continue as clinically indicated.
  • Second-line for dermatophyte-, first line for non-dermatophyte- onychomycosis: oral Itraconazole electronic Medicines Compendium information on Itraconazole 200mg daily for 3 months or 200mg bd for 7 days repeated monthly for 2 months for finger- and 3 months for toe-nails.
  • Combined treatment with topical Amorolfine 5% nail lacquer, if response to oral monotherapy likely to be poor, e.g. in proximal nail disease.
  • Third-line oral fluconazole 450 mg/week for 3 months for fingernails, for at least 6 months in toenails.
  • In pregnancy, treatment with azole-antifungals is contra-indicated. Although no proven risk exists with terbinafine, the manufacturer recommends deferral of treatment until after pregnancy.
  • Prevention of recurrence: regular use of anti-mycotic foot powder, cotton socks, wear toenails short, don’t share nail clippers, discard old shoes or put naphthalene mothballs inside, leave in tied plastic bag, then air the shoes.




Terbinafine electronic Medicines Compendium information on Terbinafine  (oral)
Evidence level A

Fungicidal against dermatophytes: better cure rates than other drugs

Found in nails after 1 week, persists for 6 months after stopping

Generally well tolerated

Absorption unaffected by food intake

minimal drug interactions

Serious side-effects low 0.04%

Side-effects: gastrointestinal upset, rash

Serious hepato-toxicity in pre-existing liver disease: take base-line LFTs and FBC in patients with high alcohol intake, hepatitis or haematological abnormalities.

Rare: Stevens-Johnson-Syndrome, permanent taste disturbance

Lower activity against Candida spec. than azoles.

Itraconazole electronic Medicines Compendium information on Itraconazole (oral)
Evidence level A

Better for candida and non-dermatophyte moulds

Pulsed treatment option: for 1 week every month.

Found in nails after 1 week, persists for 6-9 months after stopping.

Many drug interactions (Cytochrome P450 inhibition)

Less effective in dermatophyte onychomycosis than Terbinafine electronic Medicines Compendium information on Terbinafine ; monitoring of LFTs for continuous treatment of longer than 1 month or abnormal results.

Contra-indicated in pregnancy, congestive cardiac failure. Prolongs QT-interval.

Best absorbed with food and acidic pH.

Side effects: hepatotoxic, headaches, gastrointestinal upset.

Fluconazole   Evidence level A                 


Long half-life, once weekly dosing: reduced cost,

May increase compliance. Persists in nails 6 months after stopping.

Less drug interactions than Intraconazole.

Alternative in patients unable to tolerate terbinafine and itraconazole.

Not licensed.

Predominant excretion via kidneys, dose adjustment depending on creatinine clearance.

5.8% side effects leading to discontinuation with high dose weekly regime: headache, rash, gastrointestinal upset, insomnia

Contra-indicated in pregnancy.

Amorolfine  (Loceryl®) topical 5% nail lacquer Evidence level B

Safe. Broad-spectrum.    No systemic side effects. Once weekly application.

Oral Terbinafine electronic Medicines Compendium information on Terbinafine combined with topical Amorolfine more effective than Terbinafine alone.

Requires highly motivated and mobile patient: regular filing down of affected nail, treatment duration 6-12 months.

Cure only possible for early distal-lateral disease. Far less effective than oral medication.

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Record: 1389
  • To provide evidence-based recommendations for appropriate investigation of onychomycosis in adults.
  • To provide evidence-based recommendations for appropriate empirical or directed antimicrobial therapy of onychomycosis in adults.
  • To recommend appropriate dose, route of administration and duration of antimicrobial agents.
  • To advise in the event of antimicrobial allergy.
  • To set-out criteria for referral to specialists.
Clinical condition:


Target patient group: Adults
Target professional group(s): Pharmacists
Secondary Care Doctors
Adapted from:

Evidence base

  • Baran R, Sigurgeirsson B, de Berker DA et al. A multicentre, randomized, controlled study of the efficacy, safety and cost-effectiveness of a combination therapy with amorolfine nail lacquer and oral terbinafine compared with oral terbinafine alone for the treatment of onychomycosis with matrix involvement. Br J Dermatol 2007; 157(1): 149-57.
  • Ameen M, Lear JT, Madan V, Mohd Mustapa MF, Richardson M. British Association of Dermatologists' guidelines for the management of onychomycosis 2014. Br J Dermatol. 2014 Nov;171(5):937-58.

Evidence levels:
A. Meta-analyses, randomised controlled trials/systematic reviews of RCTs
B. Robust experimental or observational studies
C. Expert consensus.

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Approved By

Improving Antimicrobial Prescribing Group

Document history

LHP version 1.0

Related information

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