Painful scarring after circumcision can be caused by scar infections, keloids and scar stenosis, which should be further examined in order to clarify the causes. 1. Scar infection: the more common for the scar of the bacterial infection, in the scar there are often broken parts, in the case of improper treatment, can lead to bacterial invasion, and then appear in the scar of redness, swelling and pain. 2. Keloid: mostly seen in patients with keloid, the ring-shaped keloid is higher than the surface of the skin, and the keloid can be itchy, and some patients may have a tingling sensation. 3. Narrow scar: The ring-shaped scar formed after circumcision, if it is narrow, will produce greater tension in the narrow part when the penis is erected, which will cause pain in the ring-shaped scar. It is recommended to go to the hospital for examination, in order to clarify the condition, and the professional physician to give treatment for the condition.