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Onychodystrophy (fungal nail) – Information for GPs


  • Onychodystrophy refers to any abnormality of nail growth, thickness or appearance.
  • There are several possible underlying causes. Some causes listed below:
    • Fungal Infections (Onychomycosis): Can affect any part of the nail.85-90% caused by dermatophyte fungi, 5-10% by Candida species and 2-5% cases by non–dermatophyte moulds.
    • Psoriatic Nails: Most patients have chronic plaque Psoriasis, pitting is common.
    • Chronic Eczema: Irregular, ridged (corrugated surface), and thickened nails.
    • Lichen Planus: Can involve skin, mucous membranes, and/or nails. Nails may look grooved, fissured or ridged.
    • Alopecia Areata: Pitting and ridging of nails in up to 50% of cases.
    • Yellow Nail Syndrome: Green-yellow discoloration of the nail. Can be associated with bronchiectasis and chronic sinusitis.
    • Onychogryphosis: Thickened, hard, curved nails, commonly in the elderly.
    • Bacterial Infection (Pseudomonal aeruginosa, Paronychia), Herpes simplex, viral warts
    • Trauma from footwear.

Exclude Red Flag Symptoms


  • General skin and nail examination to look for causes e.g. psoriasis, fungal skin infection.
  • For suspected fungal nail infection:
    • Arrange nail clippings and /or scrapings for microscopy and culture (must wipe off all topical treatment with alcohol wipes prior to sampling).
    • Be aware of false negative results (30%). Repeat sample if high clinical suspicion.


  • If culture for fungus is negative advise nail care to keep nails short and thin.
  • Only offer anti-fungal treatment if fungal infection confirmed by mycology.
  • Fungal nail infection
    • If asymptomatic can opt for no treatment.
    • Treat if symptomatic / co-morbid conditions /associated with fungal skin infections.
    • Topical most effective for dermatophytes and candida species.
    • Over the counter topical treatment with amorolfine 5% nail lacquer, once or twice weekly to the affected nails only.
    • Duration of treatment: Up to 6 months for fingernails and 9-12 months for toenails. This is not routinely commissioned - available from pharmacy / online.
    • Oral treatment recommended if confirmed fungal infection and topical and self-care measures fail or not appropriate. For dermatophytes,
      • First line: Terbinafine 250mg once a day for 6 weeks
      • Alternate therapy: Pulsed treatment with itraconazole 200mg bd for 1 week repeated every 21 days .Two pulsed courses for fingernails, three for toenails. Monitor LFTs as per BNF.
      • Candida and non-dermatophyte infection: Oral Itraconazole as first line and terbinafine as alternate therapy at the above doses but is off label use.
  • Do not use topical and oral treatments at the same time.
  • Rarely may need nail removal if refractory or recurrent infections.
  • Podiatry referral if thickened nails, trauma due footwear, difficulty obtaining sample or need for nail avulsion in severe disease.
  • Refer to Dermatology if:
    • There is diagnostic uncertainty.
    • Treatment failure in Primary care.
    • Immunocompromised or co-existing conditions like Lichen planus, psoriasis.
    • Fungal nail infections in children: Rare and topical treatments not licensed for children under 12 years of age.

Information to include in referral letter

  • How long nail problem has been present
  • Which nails are affected
  • Results from nail clippings and filings sent for mycology
  • Any treatments that have been tried and for how long
  • Personal or family history of any skin disease
  • A close up photograph
  • Relevant past medical/surgical history
  • Current regular medication
  • BMI/smoking status

Investigations prior to referral

Nail clippings sent for mycology. Need to check adequate sample sent and may be worth repeating if first sample comes back negative

Patient information leaflets


Very useful webpage with good pictures of lots of nail problems.

General information about fungal nail infection and management

NICE CKS Fungal Nail Infection (March 2018)

Public Health England (2017) Fungal skin and nail infections: Diagnosis and laboratory investigation. (PHE 2017)

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