An anal fissure is a tear in the lining of the lower rectum anal canal that causes pain during bowel movements. Anal fissures don't lead to more serious problems. Most anal fissures heal with home treatment after a few days or weeks. These are called short-term acute anal fissures. If you have an anal fissure that hasn't healed after 8 to 12 weeks, it is considered a long-term chronic fissure.
Anal fissures are small tears or cracks on the part of the anus that opens when you pass stools— where the inside of the anus meets the outside. They are associated with pain and bleeding during bowel movements. Most will heal on their own and do not require treatment. In adults they can be caused by passing a large, hard stool, or by having frequent diarrhea. In older adults they may occur due to decreased blood flow to the area.