Onychomycosis
Onychomycosis is a fungal infection of the fingernails or toenails. Affected nails typically turn yellow, white, or brown, thicken, and may crumble at the edges. Toenails are far more commonly affected than fingernails, and the condition tends to progress slowly if left untreated.
Key points
- People with diabetes or poor circulation in the feet face higher risk, often after an existing athlete’s foot infection spreads upward.
- Terbinafine, the usual first-line choice, builds up in the nail and keeps working once the course ends, unlike the older option griseofulvin.
- Oral antifungals are preferred over topical creams because slow nail growth otherwise limits how well a cream can reach the infection.
Why nails are vulnerable in tropical climates
Heat and humidity create ideal conditions for the dermatophyte fungi that cause most cases. Communal bathing areas, swimming pools, and prolonged footwear use all raise the risk. People with diabetes or reduced circulation in the feet are more susceptible, and prior athlete’s foot (tinea pedis) frequently spreads upward to the nails.
How onychomycosis is treated
Because nails grow slowly and form a physical barrier, oral antifungals penetrate more reliably than topical creams alone. Terbinafine is the most widely used first-line agent; it accumulates in nail tissue and continues working after a course ends. Griseofulvin is an older alternative that suits certain fungal species. Both belong to the broader antifungals group. Treatment courses typically run several months, reflecting nail regrowth time rather than drug potency.
If a nail becomes painful, develops an odour, or shows signs of spreading infection into surrounding skin, a clinician should assess it promptly.