Ask the doctor: I have a fungal toenail infection that I can’t get rid of. Is there anything that will work?

Dr Grant replies: You may have a form of fungal toenail infection also called onychomycosis, which is a common nail disorder that accounts for about 50 to 60pc of abnormal nails. It usually involves the toenails but can also affect the fingernails. In order to get a formal diagnosis toenail clippings are sent to a local hospital to identify the causative agent typically being one of the three: dermatophyte, yeast, or non-dermatophyte mould onychomycosis. Dermatophyte infections, also called tinea unguium, are most common, accounting for more than half of all nail infections. Candida albicans is a common yeast infection that often occurs in association with frequent exposure of the hands to moisture, as may occur in certain occupations healthcare workers, bartenders or, housekeepers.​

There are many presentations of the condition in terms of nail abnormalities such as discolouration (typically white opaque nail), subungual hyperkeratosis (thickening under the nail), onycholysis (nail separates or lifts from the bed), nail splitting, and nail plate destruction. If the nail is attached to the nail bed and not lifting, then it may simply be ‘white nail’, where the nail appears white and opaque but none of the other features of onychomycosis are present.

General measures to help prevent and reduce the risk of infection spreading include:

• Keep nails short and clip the affected portion of the nail.
• Minimise activities that traumatise the nail such as mani-pedicures, nail varnish (as well as nail varnish removers) and exposure to solvents and detergents.
• Always wear kitchen gloves when doing any wet work, and ideally have a pair of soft cotton gloves underneath.
• Air the toes as much as possible, change socks frequently and put on flip-flops when at home.

The most common subtype of onychomycosis is distal (towards the end of the nail), lateral (towards the outer edge of the nail) and subungual (underneath the nail) onychomycosis, which typically begins with whitish, yellowish, or brownish discoloration of a distal corner of a nail. It’s the accumulation of keratinous debris between the nail plate and nail bed that causes the nail discolouration. The big toe is often the initial site of infection, when it then tends to spread to the entire width of the nail plate and slowly toward the cuticle.

There are two other subtypes, namely white superficial onychomycosis and proximal subungual onychomycosis. The former is characterised by the appearance of dull, white spots on the surface of the nail plate that are soft and yield a chalky scale when scraped lightly. The affected area tends to spreads from the centre outward and may eventually involve the entire nail plate if treatment is not initiated. The good news with this subtype is that topical treatment is often sufficient. The latter is a relatively uncommon subtype that affects the proximal (where the nail growth begins) nail close to the cuticle and extends distally (the opposite of the most common type, distal lateral subungal).

Treatment options involve a combination of topical and oral antifungal medication, as well as physical interventions, and really depend on the severity and patient preference. Topical treatment is cheap but can be slow. If you are willing to apply a clear lacquer containing amorolfine 5pc (available over-the-counter) onto the affected toenail once per week for up to 18 months, cure is a possibility in up to 75pc of cases. Big toe nails can take 12-18 months to regrow fully. Topical treatment poses negligible risk for side effects or drug interactions compared with oral antifungal therapy. Other topical treatment options are available on a prescription only basis.​

As a general rule, if >50pc of the nail is affected, three+ nails are involved, the matrix/lunula is involved, the infection subtype is proximal subungual onychomycosis, or there is total dystrophic onychomycosis, then the addition of oral antifungal medication is recommended. The two most commonly prescribed oral antifungal agents used to treat onychomycosis are terbinafine and itraconazole. In the case of toenail infection, the former is taken daily for three months and the latter can be taken in ‘pulse therapy’ daily for one week per month and repeated a further two months for one week per month.

​Dr Jennifer Grant is a GP with Beacon HealthCheck