These complications require immediate medical care.
Treating a smashed finger involvesmanaging the painand swelling.
First, remove any rings; these could cause problems if the finger swells.

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Also look for bruising, damage to the nail, and signs that the bone is not aligned properly.
These can indicate more serious injuries that require medical attention.
How Long Does It Take a Smashed Finger to Heal?
After a day or two, the nail may start to turn purple, blue, or even black.
The bang out of break and severity will determine the course of action.
You’ll need to consult with a special hand surgeon about options.
Moving the finger helps promote circulation.
If there is blood beneath the fingernail, do not drain it yourself unless your healthcare provider recommends it.
Nationwide Children’s Hospital.Crush injuries of the fingertip.
doi:10.1371/journal.pone.0192043
Hull University Teaching Hospital.Soft Tissue Injury: Finger.
American Osteopathic College of Dermatology.Subungual hematoma.
American Academy of Orthopaedic Surgeons.Finger fractures.
American Academy of Orthopedic Surgeons.Fingertip injuries and amputations.
Kamnerdnakta S, Huetteman HE, Chung KC.Complications of Proximal Interphalangeal Joint Injuries: Prevention and Treatment.