What are the causes and treatments of onychomycosis (fungal infection of the nail) affecting multiple nails?

From the Guidelines

Multiple nail infections, also known as onychomycosis when caused by fungi, should be treated with oral antifungal medications for the most effective results, with terbinafine being the preferred first-line treatment due to its high efficacy and safety profile, as supported by the British Association of Dermatologists' guidelines 1.

Treatment Options

• The recommended first-line treatment is oral terbinafine 250mg daily for 6 weeks for fingernails or 12 weeks for toenails, as it has been shown to have a high cure rate and is generally well-tolerated 1.
• Alternative options include itraconazole 200mg twice daily for 1 week per month, repeated for 2 months for fingernails or 3 months for toenails, which can be used in patients who are unable to tolerate terbinafine or have certain contraindications 1.
• Topical treatments like ciclopirox 8% nail lacquer or amorolfine 5% nail lacquer can be used for mild cases or as adjunctive therapy, but they are less effective when multiple nails are involved 1.

Prevention of Reinfection

• To prevent reinfection, it is essential to practice good foot hygiene, including keeping nails trimmed short, dry, and clean, and wearing breathable footwear 1.
• Patients should also avoid walking barefoot in public areas and sharing toenail clippers with family members and friends 1.
• Applying an absorbent powder and antifungal powders containing miconazole, clotrimazole, or tolnaftate in shoes and on the feet can also help prevent reinfection 1.

Management of Treatment Failure

• In cases of treatment failure, the reasons for failure should be carefully considered, and alternative treatments or combination therapy may be necessary 1.
• Nail removal in combination with a further course of therapy to cover the period of regrowth may also be considered in severe cases 1.

From the FDA Drug Label

Terbinafine tablets, USP are indicated for the treatment of onychomycosis of the toenail or fingernail due to dermatophytes (tinea unguium). Ciclopirox Topical Solution, 8%, (Nail Lacquer), as a component of a comprehensive management program, is indicated as topical treatment in immunocompetent patients with mild to moderate onychomycosis of fingernails and toenails without lunula involvement, due to Trichophyton rubrum

The treatment for multiple nail infection (onychomycosis) can be managed with:

• Terbinafine (PO) for the treatment of onychomycosis of the toenail or fingernail due to dermatophytes (tinea unguium) 2
• Ciclopirox (TOP) as a topical treatment in immunocompetent patients with mild to moderate onychomycosis of fingernails and toenails without lunula involvement, due to Trichophyton rubrum 3

From the Research

Multiple Nail Infection Overview

• Multiple nail infections, also known as onychomycosis, can be caused by various organisms, but most cases are caused by dermatophytes 4.
• The infection can cause discoloration, thickening, and separation from the nail bed, and it is more common in older adults, affecting 10% of the general population, 20% of persons older than 60 years, and 50% of those older than 70 years 4.

Diagnosis of Multiple Nail Infection

• Clinical signs of fungal nail infections are non-specific, and alternative diagnoses include psoriasis and nail microtrauma 5.
• Detection of fungal structures by direct examination of a nail sample is strongly suggestive of fungal nail infection, while cases of negative direct examination with positive culture must be interpreted with caution due to frequent contamination 5.
• Histologic evaluation using periodic acid-Schiff staining increases sensitivity for detecting infection 4.

Treatment of Multiple Nail Infection

• Systemic antifungals, such as terbinafine, itraconazole, and griseofulvin, are the most effective treatment, with meta-analyses showing mycotic cure rates of 76% for terbinafine, 63% for itraconazole with pulse dosing, 59% for itraconazole with continuous dosing, and 48% for fluconazole 4.
• Topical therapy with ciclopirox is less effective, with a failure rate exceeding 60% 4.
• Antifungal lacquers, such as 5% amorolfine and 8% ciclopirox, applied to the nails cure about 30% of fungal infections and sometimes cause mild irritation 5.
• Chemical nail destruction with a combination of urea and bifonazole, followed by treatment with an antifungal ointment, can be used when the nail is markedly thickened, with cure rates close to 70% at three months when the matrix is not involved, and 40% with matrix involvement 5.

Treatment Considerations

• Treatments with potentially severe adverse effects, such as oral terbinafine, must be used with caution, as the risks may outweigh the expected benefits 5.
• Concomitant nail debridement can further increase cure rates 4.
• Laser and photodynamic therapies show promise based on in-vitro evaluation, but more clinical studies are needed 4.
• The recurrence rate of onychomycosis is 10% to 50% as a result of reinfection or lack of mycotic cure, despite treatment 4.