From the Guidelines
Hyperkeratotic toenails, also known as thickened toenails (onychogryphosis), are primarily caused by fungal infections (onychomycosis), with other contributing factors including psoriasis, trauma, aging, and poor circulation. According to the British Association of Dermatologists' guidelines for the management of onychomycosis 2014 1, onychomycosis is a fungal disease of the nails that can be caused by dermatophytes, other molds, and Candida species. The guidelines also highlight that contributing factors to this disease include occlusive footwear, repeated nail trauma, genetic predisposition, and concurrent diseases such as diabetes, poor peripheral circulation, and HIV infection, as well as other forms of immunosuppression.
Some key points to consider in the management of hyperkeratotic toenails include:
- Fungal infections are the most common cause, occurring when dermatophytes invade the nail bed and produce excess keratin 1.
- Psoriasis can trigger abnormal nail growth with thickening as the body accelerates skin cell production.
- Repetitive trauma from tight shoes or athletic activities can stimulate defensive nail thickening.
- Age-related changes naturally lead to thicker nails as circulation diminishes and growth patterns change.
- Medical conditions like diabetes or peripheral vascular disease contribute by reducing blood flow to the extremities.
Treatment depends on the underlying cause but may include:
- Oral antifungals like terbinafine (250mg daily for 12 weeks) or itraconazole (200mg twice daily for 1 week per month, for 2-3 months) for fungal infections 1.
- Topical treatments such as ciclopirox nail lacquer or urea-based creams can help soften thickened nails.
- Regular gentle filing after bathing can reduce thickness, and proper nail hygiene including keeping nails dry and wearing breathable footwear helps prevent worsening.
- Professional podiatric care may be necessary for severe cases, especially for those with diabetes or circulation problems who should avoid self-treatment 1.
From the Research
Causes of Hyperkeratotic Toenails
Hyperkeratotic toenails, also known as thickened toenails or onychogryphosis, can be caused by various factors, including:
- Fungal infections, primarily dermatophytes and non-dermatophyte yeasts or moulds 2, 3, 4, 5
- Bacterial infections, such as those caused by gram-negative bacteria like Pseudomonas aeruginosa and gram-positive bacteria like Staphylococcus aureus 4
- Nail hyperkeratosis and leukonychia, which are useful diagnostic pointers for fungal nail infections 3
- Matrix involvement, which has important implications in the choice of treatment 3
Fungal Infections
Fungal infections are the most common cause of hyperkeratotic toenails. The most common causative agents of onychomycoses are:
- Trichophyton rubrum, a dermatophyte 2, 4
- Candida albicans, a non-dermatophyte yeast 2, 4
- Non-dermatophyte molds (NDMs), such as Fusarium species and Onychocola canadensis 4, 5
Treatment Options
Treatment options for hyperkeratotic toenails include:
- Topical antifungal agents, such as amorolfine and ciclopirox 3, 4
- Oral antifungal medications, such as terbinafine, itraconazole, and fluconazole 2, 3, 4, 5
- Combination treatment of oral terbinafine with topical terbinafine and 10% urea ointment 6
- Chemical nail destruction with a combination of urea and bifonazole, followed by treatment with an antifungal ointment 3
- Surgical nail avulsion, which carries a risk of local infection and permanent nail dystrophy 3