The head of the index finger refers to the end of the index finger knuckle, appear to have bubble swelling pain thickening symptoms may be caused by rheumatoid arthritis, tenosynovitis, soft tissue injuries and other diseases. 1. Rheumatoid arthritis: due to cold stimulation or nutritional deficiencies and other reasons can lead to damage to the joints, thus causing joint swelling, pain and other discomfort. 2. Tenosynovitis: long-term use of the fingers for exercise will lead to repeated friction between the tendon sheath and the tendon, which will cause damage to the tendon sheath and the surrounding tissues, resulting in aseptic inflammation, which will lead to swelling, foaming and thickening of the head of the index finger. 3. Soft tissue injury: the soft tissue of the index finger head in the external impact or pulling, pinprick, etc., will lead to soft tissue damage, exposure to the outside air, but also increase the local inflammation of infection, thus causing swelling and pain in the index finger head. The head of the index finger with blisters swelling pain thickening and infection, dermatitis and other factors. Therefore, when the head of the index finger blisters swelling pain coarsening, it is recommended to immediately go to the hospital to identify the cause of the disease and targeted treatment.