What should you know about dark bruise under toe nail?

A trapped collection of blood can develop beneath the nail after stubbing a toe, dropping something on it, or wearing footwear that repeatedly presses the nail. The toe may be sore and the colour can remain while the nail grows forward. A dark nail can also result from Nail Fungus or Nail Psoriasis, which may cause thickening, lifting, crumbling, pits, or other colour changes.

The pattern matters: a bruise usually follows a clear injury or pressure event, while unexplained pigment, a mark that extends onto nearby skin, or a change that does not move with nail growth needs a clinician's assessment.

Wear roomy footwear, protect the toe from further knocks, and keep the nail clean and dry. Do not drill, puncture, or remove the nail yourself. If the injury is fresh and swollen, brief cold application wrapped in cloth may ease discomfort. Photograph the nail and check whether the dark area moves toward the tip as the nail grows. Avoid covering an unexplained mark with polish before an examination.

Arrange prompt care for severe or increasing pain, marked swelling, an open wound, drainage, inability to bear weight, or a toe that looks deformed. Have an unexplained, widening, persistent, or irregular dark mark assessed, particularly if it reaches the skin beside the nail. A clinician may examine the nail and decide whether testing is needed.

Ask whether the colour is moving with nail growth, whether the nail surface suggests Nail Psoriasis or Nail Fungus, whether pressure from footwear contributed, and whether Oral Antifungal Treatment would be appropriate only if fungus is confirmed.