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. A chronic fissure may need medical treatment.
Chronic anal fissure: 2% topical diltiazem hydrochloride
Anal Fissure: Symptoms, Causes, Diagnosis, and Treatment
An anal fissure is a break or tear in the skin of the anal canal. Anal fissures may be noticed by bright red anal bleeding on toilet paper and undergarments, or sometimes in the toilet. If acute they are painful after defecation,  but with chronic fissures, pain intensity often reduces. Anal fissures usually extend from the anal opening and are usually located posteriorly in the midline, probably because of the relatively unsupported nature and poor perfusion of the anal wall in that location. Fissure depth may be superficial or sometimes down to the underlying sphincter muscle. Untreated fissures develop a hood like skin tag sentinel piles which cover the fissure and cause discomfort and pain.
Ask the doctor: What can I do about an anal fissure?
A patient presents with severe anal pain, lasting hours after each bowel movement. She notices some intermittent bleeding with defecation. She comes to the office with the presumed diagnosis of hemorrhoids.