What should you know about bruised nail turning green?

A subungual haematoma is blood trapped under the nail after impact, pressure, or repeated friction. As that blood breaks down, its colour can shift from red or purple toward brown, greenish, or black. A green patch can also develop when the nail plate has lifted and moisture remains in the space underneath; certain bacteria can produce green pigment in that setting. Colour alone cannot distinguish these causes.

Notice whether the nail is lifting, the surrounding skin is tender or swollen, or there is drainage or an odour. The bruise itself should gradually move outward as the nail grows. A mark that stays fixed, spreads, or appears without a clear injury deserves a clinician’s examination.

Keep the nail clean and dry, trim only loose edges, and avoid picking, drilling, or covering it with polish while the colour is changing. Wear roomy footwear if a toe is affected and protect the nail from another knock. Do not try to drain it at home. A clinician can decide whether pressure relief, a swab, or another treatment is appropriate; nail procedures are described in [Nail Surgery](/treatments/surgical-dermatology/nail-surgery/).

Take a clear photograph and note when the colour changed. If the nail is partly detached, do not pull it off, because the attached portion helps protect the nail bed.

Arrange prompt medical care for increasing pain, warmth, swelling, pus, a spreading green area, fever, or red streaking. Seek urgent assessment after a crush injury if the nail is badly split, the finger or toe looks deformed, or movement is difficult. A clinician should also assess a persistent or unexplained dark or green nail change, particularly when the nail is not growing outward with the rest of the nail.

Ask whether the colour fits a healing haematoma, a lifted nail with bacterial growth, or another nail disorder; whether the nail bed is injured; and whether a sample or follow-up visit is needed. You can also ask how to cover the nail safely during daily activities.