Does anal fissure cause blood in stool?

An anal fissure is a small tear in the lining at the opening of the anus. Passing a hard or large stool can stretch the area and reopen the tear. Blood may be noticed on toilet paper, on the outside of the stool, or in the toilet. Burning or cutting pain during and after passing stool can occur alongside the bleeding.

Blood in stool has several possible causes, so the pattern matters. Bleeding that is mixed through the stool, very dark stool, or bleeding without anal pain needs medical assessment rather than being assumed to be a fissure.

Aim to keep stools soft by drinking fluids and including fibre-containing foods in meals. Avoid straining or delaying a bowel movement when you feel the urge. A warm bath can soothe the area after passing stool, and gentle cleaning with water may be less irritating than vigorous wiping.

Arrange a clinical review if pain or bleeding continues, returns often, or makes bowel movements difficult. A clinician can check for a fissure and discuss measures such as stool-softening treatment or prescription treatment when appropriate.

Seek urgent care for heavy bleeding, black or tar-like stool, fainting, severe weakness, severe abdominal pain, fever, or bleeding with repeated vomiting. Get prompt medical advice if bleeding persists, changes pattern, or comes with an unexplained change in bowel habits.

Ask whether the appearance and location of the tear fit an anal fissure, whether constipation is contributing, and which stool-softening or topical treatments are suitable for you. Mention any medicines that affect bleeding and any family history of bowel disease.