Causes and Risk Factors of Anal Fissure

Table of Contents
View All
Table of Contents

An anal fissure is a tear or a break in the skin of the anus. The anus is the opening in your bottom through which stool (fecal matter) leaves the body. An anal fissure can occur in anyone but is common in babies and children. A fissure can be painful and bleed, but it usually gets better with home treatment.

This article will discuss the most common causes of anal fissures.

Woman on couch feeling discomfort from anal fissure

Vadym Pastukh / Getty Images

Common Causes

An anal fissure, in general, is caused by something that damages the interior of the anus, such as hard stool due to constipation. It could also be related to having a disease or condition that affects the immune system of the anus.

Blood in the Stool As a Symptom

An anal fissure may cause blood in or on the stool. Even when it's thought that blood either coming from the rectum or seen on toilet paper could come from a fissure, it's still important to see a healthcare provider for a diagnosis.

This is because blood in the stool is never normal. It could be caused by one of many different conditions, including some that are uncommon but serious.

Some of the causes of an anal fissure include the following:


Constipation is when you have a hard stool that is difficult to pass. Sometimes constipation can lead to firm stools that are also large and can stretch and tear the anus. The symptoms of an anal fissure caused by constipation can include stools with blood on them and pain while having a bowel movement.

This cause of anal fissures tends to be common in babies and children. Some children will avoid pooping because the anal fissure causes so much pain, which worsens constipation, leading to more pain. Getting back to having regular bowel movements is important in stopping this cycle.


Diarrhea is frequent, watery, loose stools. Having constant bowel movements and wiping to get clean could lead to irritation and a break or tear in the anus. Chronic diarrhea can happen with several common digestive conditions, including celiac disease, irritable bowel syndrome (IBS), and inflammatory bowel disease (IBD).

Diarrhea can also sometimes be a sign of constipation. When a hard stool is blocking the last part of the colon (the rectum), loose stool may be able to leak out around it. It appears as though the problem is diarrhea when, in fact, it is constipation. This is also called overflow or paradoxical diarrhea.

Sexually Transmitted Infections (STIs)

Some infections that are spread through sexual contact may contribute to the development of an anal fissure. Syphilis is one STI that is associated with anal fissures. If an STI is the cause, the infection will need to be treated. A culture or a biopsy of the anal fissure may be used to identify the type of infection involved.

Inflammatory Bowel Disease

IBD is a group of conditions that include ulcerative colitis, Crohn’s disease, and indeterminate colitis. Some major signs of IBD are inflammation in the digestive tract and chronic diarrhea. These could contribute to the development of a fissure. 

An anal fissure related to IBD is not common, and there isn’t much research on the diagnosis and treatment of fissures in people with IBD. Anal fissures are estimated to occur in about 4% of people with IBD.

Human Immunodeficiency Virus (HIV)

An anal fissure may start with ulceration related to HIV. There is a lack of evidence about the cause of anal fissure in the setting of HIV. It may or may not help to lower the risk by ensuring HIV is well-controlled with antiretroviral medications.


Having a baby through vaginal delivery can cause an anal fissure. It occurs due to the force of the baby’s head emerging during delivery. This type of anal fissure may be more common after a difficult birth or when instruments were used to help deliver the baby.

Other Trauma

Trauma can cause muscles in the anus to be irritated or stretched. This could be from inserting something into the anus that causes a tear.


Though a rare occurrence, the bacterial infection tuberculosis can cause lesions (sores) on the skin, including in the anus. Lesions on the skin occur in less than 2% of people with tuberculosis. Some of these may involve the anus and lead to a fissure.

Being Comfortable With a Healthcare Provider

It's not always easy to go to a healthcare provider to talk about bowel movements, pain in the bottom, or blood in the stool. However, it's important to remember that healthcare providers are there to help you get better.

You won't be the first patient with anal pain they've seen, and they won't be shocked or embarrassed when you describe your symptoms. Try to be honest. It's OK to admit that it's difficult for you to discuss the condition and to ask for help.

Lifestyle Risk Factors

The most common cause of anal fissures is chronic constipation. Treating constipation or preventing it in the first place will be helpful in avoiding the development of a fissure. 

In many cases, constipation can be treated with at-home measures. These can include:

  • Diet: Eating a diet high in fiber can help ensure that stools are soft and easy to pass. Fiber supplements may also be beneficial.
  • Hydration: Keeping hydrated is important in making sure stool can pass through the large intestine without becoming too hard. Drinking enough water or other fluids may help alleviate constipation.
  • Exercise: Exercise is important for overall health and may help produce regular bowel movements.


An anal fissure is a sore or tear in the anal canal. It can be acute (sudden) or chronic (long lasting). Most people can recover from a fissure with at-home treatments. Some risk factors for fissure cannot be changed but others, such as constipation, might be treated or prevented to lower the risk of an anal fissure.

A Word From Verywell

An anal fissure is a challenging, sometimes embarrassing, and painful problem to deal with. In children especially, it can be a shock to see blood on the stool. However, it’s common in children, and they usually do well with treatment.

It’s important to know that a fissure can be treated. Talking about it with a healthcare provider can help you get on the right track. Most people will heal without complications. 

6 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. Jamshidi R. Anorectal complaints: hemorrhoids, fissures, abscesses, fistulae. Clin Colon Rectal Surg. 2018;31(2):117-120. doi:10.1055/s-0037-1609026 

  2. Stewart DB Sr, Gaertner W, Glasgow S, Migaly J, Feingold D, Steele SR. Clinical practice guideline for the management of anal fissures. Dis Colon Rectum. 2017;60(1):7-14. doi:10.1097/DCR.0000000000000735

  3. Malaty HM, Sansgiry S, Artinyan A, Hou JK. Time trends, clinical characteristics, and risk factors of chronic anal fissure among a national cohort of patients with inflammatory bowel disease. Dig Dis Sci. 2016;61:861-864. doi:10.1007/s10620-015-3930-3

  4. Gardner IH, Siddharthan RV, Tsikitis VL. Benign anorectal disease: hemorrhoids, fissures, and fistulas. Ann Gastroenterology. 2020;33:9-18. doi:10.20524/aog.2019.0438

  5. Wu S, Wang W, Chen H, Xiong W, Song X, Yu X. Perianal ulcerative skin tuberculosis: a case report. Medicine (Baltimore) 2018;97(22):e10836. doi:10.1097/MD.0000000000010836

  6. MedlinePlus. Constipation - self-care.

By Amber J. Tresca
Amber J. Tresca is a freelance writer and speaker who covers digestive conditions, including IBD. She was diagnosed with ulcerative colitis at age 16.