What should you know about bad nail fungus?

A severely affected nail may become difficult to trim, rub against footwear or separate from the nail bed. Improvement is slow because healthy nail must grow forward while treatment controls the infection.

Fungal infection can begin at the nail edge and extend deeper, causing yellow, white or brown colour, debris beneath the nail, distortion and brittleness. Nearby skin may also peel or itch if athlete's foot is present.

Appearance alone cannot confirm fungus. Injury, psoriasis and other nail disorders can look similar, so a clinician may take nail clippings or scrapings before recommending a long course of treatment.

Keep the nail short without cutting into tender skin, dry feet carefully, change damp socks and avoid sharing nail tools. Disinfect or replace footwear as advised, and treat scaling between the toes so fungus is less likely to move between skin and nail.

Treatment depends on how many nails are involved, how deeply the infection extends, other medicines and general health. A topical antifungal may suit limited disease, while an oral antifungal may be considered for deeper or widespread infection. Laser treatment and nail surgery are options in selected situations rather than automatic first choices.

Arrange a medical assessment if the nail is painful, increasingly thick, lifting, spreading to other nails or not improving with appropriate self-care. Seek prompt help for redness, warmth, swelling, pus, an open wound or rapidly worsening pain around the toe or finger.

Get advice early if you have diabetes, reduced circulation, reduced sensation or a weakened immune system, because damaged skin around an infected nail deserves closer attention. Sudden dark pigment, especially without a clear injury, also needs clinical examination rather than antifungal self-treatment.

Ask whether the diagnosis should be confirmed with a nail sample, which option fits the depth and extent of infection, and whether your medicines or health conditions change the choice. It is also useful to ask how to apply treatment correctly, which unwanted effects require a call, and how progress will be assessed as the nail grows.