Bruising Under a Nail After an Injury

An impact can break tiny blood vessels in the tissue beneath the nail. The blood has nowhere to spread, so it may look red, purple, brown, or black through the nail. Tenderness and pressure are common early on. The nail may later loosen or shed while a new nail grows from its base. The colour should gradually move toward the tip as the nail grows. A mark that does not follow nail growth, changes without a clear explanation, or extends into the surrounding skin deserves a clinician’s opinion.

Protect the finger or toe from further knocks and keep the nail clean and dry. For the first day, a wrapped cold pack held against the area for short periods may ease swelling; do not place ice directly on skin. Keep the limb raised if it throbs. Do not pierce, drill, or pull off the nail yourself. Use an appropriate pain reliever only if it is normally safe for you and follow its label. If the nail edge is catching, cover it lightly rather than cutting into attached skin. A clinician can decide whether pressure needs releasing or whether an underlying fracture should be checked.

Arrange urgent medical assessment if pain is intense or worsening, the nail is partly torn, the wound is deep, the finger or toe looks crooked, movement is difficult, or there is numbness. Seek care for increasing warmth, redness, swelling, pus, or fever, which can signal infection. Children may need assessment after a crush injury even when the nail looks only mildly bruised. If the discoloration appeared without a remembered injury, it should be examined rather than assumed to be a bruise.

Ask whether the nail bed or bone may be injured, whether the blood needs treatment, how to dress a lifted nail, and what changes should prompt a return visit. You can also ask how long normal nail growth may take and whether your medicines or health conditions affect healing.