An anal fissure is a small tear in the thin, moist tissue that lines the anus. The anus is the muscular opening at the end of the digestive tract where stool exits the body. Common causes of an anal fissure include constipation and straining or passing hard or large stools during a bowel movement. Anal fissures typically cause pain and bleeding with bowel movements. You also may experience spasms in the ring of muscle at the end of your anus, called the anal sphincter.
Anal fissures are very common and can affect people of any age. Most anal fissures get better with simple treatments, such as increased fiber intake or soaking in a warm-water bath. Some people with anal fissures may need medicine or, occasionally, surgery.
1- Medical Treatment:
The goal of treatment is to relieve pain and discomfort, and heal the torn lining. Acute anal fissures the ones that don't last longer than 6 weeks are common and usually heal on their own with self-care. Chronic anal fissures those that last longer than 6 weeks may need medicine or surgery to help them heal.
2- Botox injections:
When topical treatments don't work, injecting botulinum toxin type A (Botox) into the sphincter is sometimes the next step. Botox injections temporarily paralyze the sphincter muscle, relieving pain and encouraging healing in 60% to 80% of patients. You may not be able to control your bowel movements or passing gas, but it's temporary. The dose is extremely low, so there is no risk of botulism poisoning.