A bruised finger is usually the result of an impact or trauma on the finger; bleeding occurs beneath the skin, and swelling and pain are likely to follow the impact. In most cases, this is not a serious injury, but a bruised finger may be an indicator of a much more serious problem, such as a bone fracture or muscle tear. If pain and swelling lasts more than 5-10 days, it is advisable to seek medical attention. If the finger loses mobility for more than 5-10 days, it is also advisable to seek a doctor's advice.
When the injury occurs, it is a good idea to apply the RICE treatment: rest, ice, compression, and elevation. Icing the injury will help prevent some swelling and will numb the pain; compression and elevation will help promote blood flow to the injury, thereby promoting faster healing for the bruised finger. Resting the injured finger for several days may be necessary to help prevent further injuries and to promote healing; if the finger needs to be immobilized, you can tape that finger to one of your other fingers for added stability, but remember that this can cut down mobility in two fingers, not just one.
Some symptoms can linger for a few weeks, such as discoloration or stiffness. This is generally considered normal, but if the pain from the injured finger worsens or persists beyond two weeks, the finger may have sustained a fracture, tendon tear, or muscle tear. Minor occurrences of these injuries will generally heal on their own, but serious injuries will require medical attention. If the pain is intense, see a doctor immediately to determine the best course of action. Severe fractures, in which the finger bone cracks, may require surgical attention. Dislocations, in which a bone pops out of its socket, may also require medical attention, so be sure to see a doctor immediately if such an injury occurs.
If a bruised finger occurs but no impact caused it, or no other cause seems to be apparent, you should consult a doctor immediately, as this may be an indicator of a much more serious problem. Some diseases and disorders can lead to finger bruising, and if you are currently taking any medications, you may need to consult your doctor to figure out if those medications may be leading to the swelling. If so, you may need to change your medications.