Complications of anal fissure can include:
Anal fissure that fails to heal. An anal fissure that doesn’t heal can become chronic, meaning it lasts for more than six weeks.

Anal fissure that recurs. If you’ve experienced anal fissure once, you have an increased risk of another anal fissure.
 

A tear that extends to surrounding muscles. An anal fissure may extend into the ring of muscle that holds your anus closed (internal anal sphincter). This makes it more difficult for your anal fissure to heal. An unhealed fissure may trigger a cycle of discomfort that may require medications or surgery to reduce the pain and repair or remove the fissure.