What Causes Diverticulitis?

Diverticulitis is the inflammation or infection of the diverticula, small pouches in the intestinal tract caused by diverticulosis. Typically seen in people over 60, diverticulitis is responsible for about 371,000 emergency room visits per year in the United States.

Diverticulitis can lead to severe infection, bowel blockage, or a fistula if untreated. Decreasing the risk of diverticulosis through lifestyle changes can help prevent diverticulitis.

This article will discuss the causes, symptoms, risk factors, and prevention of diverticulitis.

A man holding his stomach in pain

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What Is Diverticular Disease?

Diverticular disease is the formation of diverticula (pouches or bulges) in the colon. Diverticular disease is often discovered during a colonoscopy, and the diverticula appear as potholes in the intestinal wall. About 50% of people over 60 have diverticular disease; in most cases, it is asymptomatic. Some researchers believe that diverticular disease is linked to a diet low in fiber.

Is Diverticulitis a Serious Condition?

When diverticula become inflamed or infected, it is called diverticulitis. Diverticulitis is categorized as either uncomplicated or complicated. If untreated, complicated diverticulitis can lead to severe health conditions and death.

Diverticulitis Causes

Although the exact cause of diverticulitis is not fully understood, experts believe that when the diverticula are obstructed with stool, the mucosa becomes inflamed, resulting in microtears, trauma, infection, and ischemia (insufficient blood supply to an organ or other area of the body). Complicated diverticulitis occurs in about 12% of people with the condition.

What Is the Main Cause of Diverticulitis?

Many factors can cause diverticulitis. Diet, lifestyle, genetics, and certain medications can affect the gut microbiome (environment of microorganisms within the digestive system), resulting in chronic inflammation and altered colon motility leading to diverticulitis.

Who Is Most at Risk for Diverticulitis?

Around 5% of people with diverticulosis have a risk of getting diverticulitis. Although most of these people are over 60, the incidence of the disorder in people 40 to 49 has increased by 132% over the past three decades.

Other factors that may contribute to the occurrence of diverticulitis are:

  • Race: White Americans are more likely to be diagnosed with diverticulitis than Black or Latinx Americans.
  • Gender: Diverticulitis is more common in people assigned male at birth before age 60 than in people assigned female at birth.
  • Habitation: Those living in urban areas and developed countries are hospitalized with diverticulitis more often than their counterparts.
  • Socioeconomic: Hospitalizations due to diverticulitis are more common in people with lower incomes and educational levels.

What Are the Signs of Diverticulitis?

Symptoms of uncomplicated diverticulitis may be left-sided abdominal pain, constipation, or diarrhea. Signs of complicated diverticulitis include:

  • Severe abdominal pain
  • Bowel perforation (hole in the intestine)
  • Fistula (an abnormal connection between two organs or passageways)
  • Abdominal abscess (wound in the abdomen)
  • Peritonitis (infection of the lining of the abdominal cavity)

If you have a history of diverticulosis and have severe abdominal pain accompanied by fever and chills that make you shake, you should be immediately evaluated by a healthcare provider.

Can Diet Trigger Diverticulitis?

Until recently, it was thought that high-residue foods such as popcorn, seeds, corn, and nuts could be responsible for developing diverticulitis. However, there is no sound data that supports this belief. Preventing constipation by adding fiber to your diet may or may not help reduce the risk of getting diverticulitis.

Is Diverticulitis Hereditary?

There is growing evidence that diverticulitis could be hereditary. Diverticulosis is a precondition to diverticulitis, and even in asymptomatic cases, some people can have chronic inflammation leading to complicated diverticulitis.

The TNFSF15 gene controls inflammation, and mutations of this gene could be responsible for inflammatory bowel disease (IBD) and diverticulitis, especially in people who experience early onset of the disorder. Additionally, mutations in the LAMB4 gene could cause poor colonic motility (passage of waste through the intestines), increasing the risk of diverticulitis.

More research is needed to verify if diverticulitis is hereditary, but evidence shows that environmental and genetic factors cause the disorder.

What Causes Diverticulitis to Flare Up?

About 4% to 10% of people with diverticulosis have what's known as smoldering diverticulitis. Despite antibiotics, these people have pain, increased white blood cell (WBC) counts, fever, and evidence of diverticulitis on a computed tomography (CT) scan. Additionally, the following are percentage rates for diverticulitis flare-ups:

  • A recurrence rate of 8% occurs within one year of recovering from the initial diverticulitis incident and 20% recurs within 20 years.
  • After the second flare-up, the risk of recurrence is 18% at one year and 55% at three years.
  • After the third flare-up, the risk of recurrence is 40% at three years.

Contributing factors for diverticulitis flare-ups are:

  • A young age of diverticulitis onset
  • The extent of intestinal involvement
  • Family history of diverticulitis
  • Smoking
  • Being male
  • Having obesity

Although some people will experience flare-ups, complications from diverticulitis (perforation, for example) occur more often during the first episode than in subsequent episodes.

Additional Risk Factors for Diverticulitis

Lifestyle plays a role in the development of diverticulitis. The following are modifiable lifestyle factors that contribute to diverticulitis:

Although more research is needed, statins (cholesterol-lowering drugs), metformin (an antidiabetic medicine), and calcium channel blockers (blood pressure–lowering drugs) may decrease the risk of diverticulitis.

Prevention Tips for Diverticulitis

If you've been diagnosed with diverticular disease, the following tips could help prevent diverticulitis:

  • Maintaining a healthy body weight
  • Getting daily exercise
  • Quitting smoking
  • Eating less red meat
  • Getting 14 grams of fiber per 1,000 calories consumed
  • Staying hydrated
  • Reducing the use of NSAIDs, if possible


Diverticulitis is the inflammation or infection of the diverticula, small pouches in the colon from diverticular disease. Complicated diverticulitis can result in severe medical conditions. If left untreated, it can be fatal. Although the cause is not fully understood, environmental and genetic factors influence the prevalence of diverticulitis.

Living a healthy lifestyle is one way to prevent diverticulitis. If you've been diagnosed with diverticular disease, inform a healthcare provider of any new abdominal pain, fever, chills, or blood in your stool.

9 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.
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By Serenity Mirabito RN, OCN
Serenity Mirabito, MSN, RN, OCN, advocates for well-being, even in the midst of illness. She believes in arming her readers with the most current and trustworthy information leading to fully informed decision making.