Fingernail Injuries and Black Fingernails

When you injure your fingertip and the nail starts turning black, it can be tempting to think "It's just a fingernail so it will be fine in a few days". Unfortunately that's not always the case, and sometimes medical treatment is required to keep it from getting worse. An injured nail that turns black is called "Subungual Hematoma", which just means blood under the fingernail.

WebMD: If the pain is mild and the hematoma (blood collection) is less than 25% of the area under the nail, then home care is recommended.

If the hematoma is 25% or more of the underlying nail area, then medical attention is required.

If the injury that causes the subungual hematoma is severe enough to cause intense pain and tenderness or if the blood collection beneath the nailbed occupies 25% or more of the nail area, you should seek medical attention. The mechanism of injury for this condition can cause a fracture to the bone at the end of the finger or toe or a laceration to the nailbed under the nail that may require further medical attention.