Nail Discoloration: Causes, Diagnosis and Treatment

Nail discoloration can follow injury, infection, inflammation or pigment production, and examination helps identify the right treatment.

A nail may turn yellow, green, white, brown, grey or black. The change can involve the whole nail, a narrow or broad band, the tip, or the skin beneath the nail. Texture may also change: the nail can become thick, brittle, ridged, lifted or crumbly. Pain, pressure, tenderness or drainage are useful details, especially after a knock, manicure or prolonged moisture.

Arrange prompt medical assessment for a new dark band, pigment that extends onto the surrounding skin, bleeding without a clear injury, a rapidly changing nail, or persistent pain and swelling. Seek urgent help for severe trauma, loss of feeling, a cold or pale finger or toe, or signs of spreading infection such as increasing redness, warmth and pus. Do not cover a changing nail with polish before it is examined.

These causes are listed alphabetically, not as a likelihood ranking. Green Nail Syndrome can create green colour in a lifted or moist nail. Melanonychia produces brown or black pigment bands. Nail Fungus may cause yellowing, thickening and crumbling. Nail Psoriasis can cause pits, separation and colour change. A Bruised Nail may appear red, purple, brown or black after pressure or impact.

The clinician examines the colour, surface, thickness, attachment and surrounding skin, then compares affected nails with the others. They ask about injury, footwear, swimming, wet work, nail products, skin disease and how the mark has changed as the nail grows. A clipping, scraping or other sample may be checked when fungus is suspected. A persistent pigment band may need specialist assessment rather than treatment based on appearance alone.

A Bruised Nail may be observed when the injury is minor, while a clinician assesses significant pressure or damage. Nail Fungus may need a confirmed diagnosis and a topical or oral antifungal plan; oral antifungal treatment is prescribed only when appropriate for the person. Green Nail Syndrome calls for moisture control and targeted medical advice. Nail Psoriasis is treated as part of the inflammatory condition. A changing pigment band should be assessed before cosmetic concealment or removal is considered.

Keep nails trimmed without cutting the surrounding skin, dry hands and feet carefully, and wear footwear with enough room at the toes. Use gloves for prolonged wet work and avoid sharing nail tools. Clean and disinfect personal tools, and allow the nail to recover from repeated artificial enhancements if it becomes lifted or sore. Treat cuts promptly and avoid picking at discoloured areas.

Check for thickening, pits, ridges, lifting, crumbling, tenderness, swelling, odour, drainage or a changing mark in the skin around the nail. Note whether similar changes affect fingernails, toenails, skin or joints. A dated photograph can help show whether a band or patch is moving outward with nail growth.

Nail colour alone cannot identify its cause. Examination can separate an injury from infection, inflammation or pigment production and can prevent an unsuitable treatment from delaying the right assessment. Bring a list of nail products, medicines and recent injuries to the appointment.