Swelling and pain of the right index finger may be related to trauma, purulent dactylitis, arthritis, onychomycosis, mosquito bites and so on. 1. Trauma: Trauma to the right index finger, such as smashing and squeezing, can cause local capillary rupture and bleeding and soft tissue edema, which will cause swelling, pain and activity limitation. 2. Infection: Infection of the right index finger may result in purulent dactylitis, and the swelling of the tissues compresses the peripheral nerves, resulting in obvious swelling and pain. 3. Arthritis: Arthritis of the right index finger, such as rheumatoid arthritis and gouty arthritis, can cause obvious swelling, pain, and limitation of flexion and extension during the attack. 4. Trenchitis: when the nail groove at the end of the right index finger is infected and forms trenchitis, the inflammatory reaction will also cause symptoms of swelling and pain at the end of the right index finger. 5. Mosquito bites: The right index finger can be swollen and painful after an allergic reaction to a mosquito bite. There are many reasons for the swelling and pain of the right index finger, if it is difficult to relieve, it is recommended that the patient go to the hospital for medical examination, to clarify the cause of the disease, and then follow the doctor’s instructions for treatment.