What Is Diverticulitis?

A Form of Diverticular Disease

Diverticulitis is a condition that affects the diverticula, small, bulging pouches or sacs that grow inside the walls of your colon (large intestine). A small tear can occur in the colon's lining when diverticula become inflamed. This can lead to an infection.

Inflamed or infected diverticula cause diverticulitis. The problem affects more than 50% of U.S. adults over age 60. It causes severe abdominal pain. Treatment may or may not be needed based on your symptoms.

This article describes diverticulitis symptoms, causes, diagnosis, and treatments. It also covers ways to avoid flares and reduce your risk.

person holding stomach in pain

Vladimir Vladimirov / Getty Images

When to Seek Emergency Treatment for Diverticulitis

Symptoms of diverticulitis can quickly progress to a life-threatening situation. Call 911 or seek emergency care if you have any of the following symptoms accompanied by sudden and severe abdominal pain:

Diverticulitis Symptoms: Signs of a Flare

Diverticulitis symptoms result from inflammation of the diverticula, which are small bulging pockets that form in the colon wall due to age. When a hole or tear perforates a diverticulum, it becomes inflamed and can cause many symptoms.

Mild (Acute) Diverticulitis

Symptoms of a mild (acute) diverticulitis attack involve sudden and severe abdominal pain that usually occurs on the lower left side, though it can sometimes affect the lower right side. The pain typically lasts for several hours or days. You may get relief when you have a bowel movement.

Any of the following symptoms may accompany the pain of diverticulitis:

Severe Diverticulitis

Severe diverticulitis can involve repeated attacks of acute diverticulitis. It can also involve an extended course of a single diverticulitis attack that may subside but never go away. In addition to the symptoms of mild (acute) diverticulitis, severe diverticulitis can cause complications. It may also involve the following symptoms:

  • Narrow or pellet-shaped stools
  • Dark, cloudy urine
  • Passing air with urine

Does Diverticulitis Affect Your Stool?

Symptoms of diverticulitis, including changes to your stool, vary by individual.

You may notice blood in your stool. This happens when diverticular sacs bleed into your colon. The blood can appear as red specks mixed in with your stools or dark or bright red clots that pass separately. Blood can also occur due to straining during constipation, a common symptom of diverticulitis.

Rarely, you may experience diarrhea, which causes loose, watery stools. If your large intestine narrows due to advanced or severe diverticulitis, your poop may become thin or pellet-shaped.

What Causes Diverticulitis?

There is no specific known cause for diverticulitis.

Diverticulitis is related to diverticulosis, in which small pouches form and push outward through weak sections in your colon's wall. These diverticula likely form when high pressure inside your colon pushes out against weak spots in your colon wall. One source of pressure may be constipation and hard stools that form as a result of eating a low-fiber diet.

The inflammation or infection of these sacs can cause small tears in the colon, resulting in the pain associated with diverticulitis. Bacteria that grow in the walls of the diverticula can aggravate the tear by causing an infection at the site.

Your risk of diverticulitis increases with the following factors:

Do Certain Foods Trigger Diverticulitis?

There isn't evidence that certain foods trigger diverticulitis.

In the past, it was advised that you should not eat nuts, popcorn, and seeds like pumpkin, sunflower, and sesame if you were at risk of diverticulitis. However, research indicates that these foods don't impact your risk of the condition. No seeds—including those in tomatoes, cucumbers, and strawberries—increase the incidence of diverticulitis.

To help prevent diverticulitis, experts advise eating a high-fiber diet with a target of 25 to 30 grams of fiber daily. Fiber can soften your stool and avoid constipation, which exerts pressure on the colon and cause the formation of diverticula. Experts advise eating the following foods to avoid diverticulitis:

  • Fruits like apples, pears, and bananas
  • Vegetables like broccoli, carrots, squash, and corn
  • Beans and legumes
  • Whole wheat pasta
  • Bran, whole wheat bread, and whole grain cereals
  • Brown and wild rice

Testing to Diagnose Diverticulitis

Diverticulitis symptoms can resemble medical conditions that affect your appendix, small bowel, gallbladder, kidneys, stomach, bladder, ovaries, uterus, or prostate. The following tests can help your healthcare provider rule out these conditions and determine whether your symptoms may be related to diverticulitis:

  • Medical history: A medical history involves gathering information about the duration and extent of your symptoms, patterns of bowel movements, your diet, other medical conditions, and medications.
  • Physical exam: A physical exam often includes measuring your blood pressure, temperature, and heart rate. Your healthcare provider may listen to your abdomen and/or use palpation to identify the location of tenderness or masses. They may also perform a digital rectal exam (DRE).
  • Blood test: A blood test, or complete blood count (CBC), may be used to identify an infection and check for signs of diverticulitis complications.
  • Pregnancy test: A pregnancy test can rule out the presence of pregnancy and ectopic pregnancy, a condition in which a fertilized egg implants in a fallopian tube or another location outside the uterus.
  • Urinalysis: A urinalysis can analyze the content of your urine to identify a urinary tract infection (UTI), which may be linked to a fistula (an abnormal connection between two body parts) from your colon to your bladder.
  • Stool test: A stool test can help identify signs of diverticular disease or other medical conditions such as inflammatory bowel disease (IBD), colon cancer, anal fissures, or infections.

If your healthcare provider suspects diverticulitis based on your symptoms and/or the results of lab tests, the following tests can provide a definitive diagnosis of diverticulitis:

  • Computed tomography (CT) scan: A CT scan of the abdomen and pelvis is considered the gold standard for diverticulitis diagnosis. This test is usually done with intravenous contrast. It provides cross-sectional, two- and three-dimensional images of the gastrointestinal tract. A CT scan is the best method for confirming diverticulitis, evaluating the severity and degree of disease, identifying complications, and diagnosing other conditions.
  • Colonoscopy: Since many symptoms of diverticulitis resemble colon cancer, a colonoscopy is usually advised after you receive medical treatment for diverticulitis. A colonoscopy to determine the presence of colon cancer is usually performed six to eight weeks after the symptoms of diverticulitis resolve.

Diverticulitis Treatment

Your need for diverticulitis treatment depends on the severity of your symptoms. For uncomplicated diverticulitis, medication is not always necessary. If your healthcare provider determines that you can benefit from treatment, they may advise the following:

For severe or complicated diverticulitis, you may require hospitalization, depending on your symptoms. Your treatment may involve the following therapies:

Diverticulitis surgery may be advised when diverticulitis causes severe damage or a potentially life-threatening condition like one of the following conditions:

The following procedures can be performed with radiology guided, traditional open surgery, or laparoscopic techniques:

  • Percutaneous CT guided abscess drainage: This procedure is the most conservative approach and usually involves an abscess over 2 inches (5 centimeters) and includes inserting a tube into the abscess to allow it to drain.
  • Partial colon resection with anastomosis: The damaged portion of the colon is removed due to fistulas, intestinal blockage, peritonitis, or an undrainable abscess. The cut ends are joined so you can eliminate waste normally.
  • Partial colon resection with colostomy: During a colostomy, the damaged portion of the colon is removed, and the healthy end of the colon is connected to a hole in the abdomen called a stoma. Your waste empties into an ostomy bag, an external pouch attached to the stoma. The colostomy can be reversed with another surgery.

Does Diverticulitis Go Away on Its Own?

Most people who develop diverticulitis can recover without treatment. About 95% of people experience an uncomplicated episode of diverticulitis. In these cases, diverticulitis usually goes away within a week. About 5% of people have complicated diverticulitis, producing persisting symptoms and requiring treatment.

Potential Diverticulitis Complications

Complications of diverticulitis are rare. Only 15% of people who have symptoms of this condition develop complications. However, these issues can be serious when they occur. The following are potential complications of diverticulitis:

  • Abscess: An abscess is a pus-filled area caused by a bacterial infection. With diverticulitis, the pocket of pus develops just outside your colon wall. Symptoms may include abdominal pain, swelling, and severe tenderness.
  • Perforation: A perforation is a hole or tear in the lining of the intestine.
  • Peritonitis: Peritonitis is a life-threatening inflammation and infection of the abdominal cavity. It can occur when pus or stool spills into your abdominal cavity due to perforation.
  • Fistula: A fistula is an abnormal pathway between two organs. A fistula between your colon and your bladder, small intestine, or vagina can develop after a severe diverticulitis flare-up.
  • Bowel obstruction: A bowel obstruction occurs when your large intestine becomes blocked, preventing food and stool from passing through your intestines. Chronic diverticulitis can cause scar tissue that develops into a life-threatening bowel obstruction.
  • Stricture: A stricture is a colon narrowing that prevents stool from passing.

How to Avoid Repeat Diverticulitis Flares

If you have a diverticulitis flare, you are more likely to have repeat flare-ups in the future. Research indicates that the risk of a recurrence seems to increase after each flare-up. Recurring flare-ups occur in about 33% of patients with uncomplicated diverticulitis.

You may be able to avoid repeat diverticulitis flares by making the following dietary and lifestyle changes:

  • Consume a high-fiber diet that includes bran cereals, whole-grain bread, fruits, and vegetables. (Add fiber to your diet gradually to avoid bloating and gas.)
  • Establish and maintain a program of cardiovascular activity.
  • Lose weight if necessary.
  • Drink at least 64 ounces of water daily to prevent constipation if you increase your fiber intake.
  • Take fiber supplements like sugar-free gummies or the powder form of a fiber laxative that contains psyllium, like Metamucil.
  • Talk to your healthcare provider about ways to avoid using NSAIDs.


Diverticulitis is a relatively common problem affecting more than half the U.S. adults over 60. The problem affects the diverticula, small, bulging pouches or sacs that grow inside the walls of your colon (large intestine).

Inflamed diverticula can cause a small tear to occur in the lining of your colon. This can lead to an infection. An inflamed or infected diverticula can cause severe abdominal pain. It usually occurs on your lower left side.

Treatment varies based on symptoms. Most cases involve mild flare-ups. These may heal on their own without treatment. Surgery may be used to remove the damaged portion of the colon when extreme complications occur.

17 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. Penn Medicine. Diverticulitis.

  2. American College of Emergency Physicians. Stomach pain.

  3. American Society of Colon and Rectal Surgeons. Diverticular disease expanded information.

  4. Harvard Health Publishing. Diverticular disease of the colon.

  5. University of Colorado Health. Diverticulitis and diverticulosis.

  6. American Society of Colon and Rectal Surgeons. Diverticular disease.

  7. Bailey J, Dattani S, Jennings A. Diverticular disease: rapid evidence reviewAFP. 2022;106(2):150-156.

  8. University of California San Francisco. Diverticulitis.

  9. National Institute of Diabetes and Digestive and Kidney Diseases. Diagnosis of diverticular disease.

  10. Minordi LM, Larosa L, Berte G, Pecere S, Manfredi R. CT of the acute colonic diverticulitis: a pictorial essayDiagn Interv Radiol. 2020;26(6):546-551. doi:10.5152/dir.2020.19645

  11. Alcantar DC, Rodriguez C, Fernandez R, Kumar S, Junia C. The necessity of a colonoscopy after an acute diverticulitis event in adults less than 50 years oldCureus. 11(9):e5666. doi:10.7759/cureus.5666

  12. Yale Medicine. Diverticulitis.

  13. American Society of Colon & Rectal Surgeons (ASCRS). Diverticular disease expanded information.

  14. Institute for Quality and Efficiency in Health Care (IQWiG). Diverticular disease and diverticulitis: treating acute diverticulitis.

  15. Onur MR, Akpinar E, Karaosmanoglu AD, Isayev C, Karcaaltincaba M. Diverticulitis: a comprehensive review with usual and unusual complicationsInsights Imaging. 2017;8:19-27. doi:10.1007/s13244-016-0532-3

  16. Hupfeld L, Burcharth J, Pommergaard HC, Rosenberg J. Risk factors for recurrence after acute colonic diverticulitis: a systematic reviewInt J Colorectal Dis. 2017;32(5):611-622. doi:10.1007/s00384-017-2766-z

  17. The University of Texas Southwestern Medical Center. Living with diverticulitis: get the full scope of symptoms, treatment, and prevention.

By Anna Giorgi
Anna Zernone Giorgi is a writer who specializes in health and lifestyle topics. Her experience includes over 25 years of writing on health and wellness-related subjects for consumers and medical professionals, in addition to holding positions in healthcare communications.