An anal fissure is a tear in the lining of the anus. Anal fissures can make bowel movements severely painful, and even cause pain that lasts for hours after you've gone to the bathroom. People who suffer from anal fissures may try to avoid defecating to prevent the pain and discomfort.
An anal fissure is usually a short-term or acute problem, with symptoms that last 6 weeks or less. Anal fissures are considered chronic when symptoms last for more than 6 weeks. Chronic anal fissures may be more difficult to treat and may indicate an underlying condition, such as Crohn's disease or ulcerative colitis.