Swelling of the thumb is usually caused by an inflammatory infection, which may be caused by nail infection or purulent dactylitis. Nail fungus is usually caused by excessive trimming on both sides of the nail when it is trimmed, and the new nail tends to grow into the flesh on both sides, leading to an inflammatory infection in the tissues of the hand over time, resulting in the formation of an abscess. It is also possible that during the process of pulling the barb, the skin was accidentally damaged and not effectively disinfected, secondary to bacterial infection, resulting in local inflammation and swelling. The abscess needs to be cut open, the pus drained out, the nail removed if necessary, and the wound changed. Purulent dactylitis tends to occur in the finger, which may have a foreign body lacerated at the finger and with bacteria, causing the finger to swell, be painful, or even have throbbing pain internally. A fine needle puncture is required, and if pus can be drawn out, the diagnosis is made. After the diagnosis is clear it usually requires incision and drainage of the pus, intravenous antibiotics, and continued dressing changes to the wound.