Why does anal fissure cause constipation?

The next bowel movement can then stretch the tear again, producing more pain and continuing the cycle. Constipation is a common presentation of Anal Fissure, but constipation also has many other causes.

A fissure is a small tear in the lining of the anus. Passing a hard stool across it can cause sharp pain. Some people respond by tightening the muscles in the area or avoiding the toilet because they expect pain. The longer stool remains in the bowel, the more water may be absorbed from it, leaving it drier and harder.

Reduced fluid intake, a low-fibre diet, limited mobility, medicines, and changes in routine can add to the problem. Treating both the tear and the stool pattern helps prevent repeated injury.

Try to respond to the urge to pass stool rather than postponing it. Fluids, regular meals, gentle movement, and fibre-containing foods can support a softer stool pattern when suitable for you. A clinician or pharmacist can advise whether a stool-softening medicine is appropriate and how to use local treatments safely.

Seek urgent medical help for severe abdominal pain, vomiting, a swollen abdomen, inability to pass stool or gas, fainting, or heavy rectal bleeding. Arrange a clinical review for continuing fissure pain, recurrent bleeding, constipation that does not improve, or an unexplained change in bowel habits.

Ask how to keep stool soft, whether any current medicines contribute to constipation, and how long to try self-care before follow-up. Describe your stool pattern, pain during bowel movements, and any blood you have noticed.