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Health Education

Diverticulosis vs. diverticulitis: What’s the difference?

Experts explain these two commonly occurring digestive disorders
Heidi Borst
By | Sep. 19, 2022 Medically reviewed by Jesse P. Houghton, MD, FACG

Maybe you’ve got low-grade abdominal pain that doesn’t seem to go away. Or maybe you’re experiencing nausea, bloating, or constipation on a regular basis. If so, you may have a condition called diverticulitis. The common digestive system disorder occurs when small pouches called diverticula form in your colon and become inflamed and infected. The presence of diverticula is called diverticulosis. Here, experts explain the difference between diverticulosis and diverticulitis, plus treatment and prevention strategies. 

What is diverticulitis and diverticulosis?

The condition diverticulosis occurs when diverticula are present. These are small, sac-like, bulging pouches that push through weak spots of the colon/large intestine. Diverticulosis is very common, occurring in about half of individuals older than 60; almost everyone will have it by the age of 80. 

What causes diverticulosis to develop in the first place? According to José Morey, MD, a musculoskeletal radiologist at Medical Center Radiologists in Norfolk, Virginia, diverticulosis tends to develop as a result of consuming a Western diet, which is low in fiber. Low-fiber diets cause constipation, which increases pressure inside the digestive tract and causes you to strain during bowel movements. Over time, these factors can cause the development of diverticula. “Eating less red meat and more fiber can help prevent their development,” Dr. Morey says. There also appears to be a hereditary component to their development.

Diverticulosis usually doesn’t cause symptoms, but can cause lower abdominal cramping in some individuals. Diverticulosis is also permanent, says Dr. Morey. That means once you develop diverticula, the pouches won’t go away. In fact, the condition can worsen. When diverticula become inflamed and infected, the condition is called diverticulitis.

“The term ‘itis’ is Latin for inflammation/infection,”  Dr. Morey says.  So any time you see it added to the end of something, it means the inflammation of the prefix. For example, hepatitis is inflammation of the liver, and pancreatitis is inflammation of the pancreas. “Hence, diverticulitis is inflammation or infection of the diverticula,” he explains.

What is the difference between diverticulitis and diverticulosis?

The National Institute of Diabetes and Digestive and Kidney Diseases defines diverticulosis as a condition in which small sacs called diverticula push through the wall of the colon. Typically, these sacs form in the sigmoid colon, which is the left lower part of the colon. But Dr. Morey says the diverticula can develop in other locations along the alimentary canal, the internal passageway from the mouth to anus, including the ascending colon and even the small intestine.

The presence of diverticula (diverticulosis) usually occurs without any symptoms, says Elena Ivanina, DO, a board-certified gastroenterologist and director of neuro-integrative gastroenterology at Lenox Hill Hospital’s Northwell Health in New York. But it is possible to experience lower abdominal discomfort and changes in bowel habits like constipation or diarrhea with diverticulosis,  says Supriya Rao, MD, a board-certified gastroenterologist at Integrated Gastroenterology Consultants in Chelmsford, MA.

Diverticulitis is a more serious condition than diverticulosis. It occurs when diverticula become inflamed and/or infected. This can happen quickly, causing complications of diverticulitis like “severe abdominal pain that is unrelenting, blood and mucus in the stool, fever, and changes in bowel habits,” Dr. Rao says. The good news? Most of the time, diverticulosis doesn’t turn into diverticulitis—in fact, most people won’t experience any symptoms or issues from diverticulosis.

What causes diverticulitis and diverticulosis?

In the United States, diverticulosis is very common. Research estimates its prevalence at less than 5% in people younger than 40. But by the age of 60, more than 50% of people will develop diverticulosis. About 25% of those with diverticulosis will develop symptomatic diverticulosis, with usual symptoms including left lower abdominal cramping and irregular bowels. The rate of diverticulosis increases with age, affecting almost everyone older than 80. In contrast, the rates of diverticulitis vary by study, with one study finding only 4% of patients with diverticulosis ever developing diverticulitis.

It is widely believed that too little fiber contributes to the development of diverticulosis. That’s because not eating enough fibrous fruits, vegetables, beans, legumes, nuts, and whole grains can lead to chronic constipation, which causes a buildup of pressure in the colon—this may allow diverticula to form. 

More research into the cause of diverticulitis is needed, but one theory is that diverticula may become infected when bacteria from stool gets pushed into the tiny sacs. The good news is that these conditions are not linked with an increase in colon cancer in the long term.

The following factors increase your risk of diverticulosis or diverticulitis:

Symptoms of diverticulosis vs. diverticulitis 

Often, diverticulosis does not cause symptoms. However, you may experience the following:

  • Abdominal cramping or pain (usually in the lower left side)
  • Abdominal tenderness
  • Bloating/swelling
  • Constipation

The most common symptoms of diverticulitis, which are present at greater intensity during a flare-up, include: 

  • Pain and tenderness in the left side of the lower abdomen
  • Fever or chills
  • Nausea and vomiting
  • Abdominal cramps
  • Rectal bleeding
  • Constipation
  • Diarrhea

It’s important to remember that some of these symptoms may be associated with a general gastrointestinal disorder such as irritable bowel syndrome (IBS), inflammatory bowel disease (IBD), celiac disease, appendicitis, gallstones, ulcers, and other digestive diseases. It’s important to receive a diagnosis from a medical professional to differentiate between these conditions and diverticular disease.

RELATED: IBD vs. IBS

To diagnose diverticular disease, your provider will perform a physical exam to check your vital signs and palpate your abdomen for tender areas or masses. This may involve a digital rectal exam. They will also thoroughly review your medical history, including your bowel movement history, diet, medical conditions, and current medications. One or more of the following tests may be ordered:

According to Dr. Rao, pockets that can form in the lining of the colon due to weaknesses in the wall, or diverticulosis, can be seen during colonoscopy. Dr. Ivanina explains that “if there is pus or inflammatory exudate seen in a diverticulum,” diverticulitis is suspected.

“On a CT scan, a pouch (diverticulum) that appears very thick with surrounding inflammatory changes is likely infected and would mean that you have diverticulitis,” says Dr. Ivanina. A CT scan can also help to determine the severity of your diverticulitis.

What is the treatment for diverticulitis and diverticulosis? 

Diverticulosis cannot be reversed, says Dr. Rao. “The best treatment is a high-fiber diet, adequate water intake (to avoid constipation), and stool softeners as needed to avoid constipation,” she says. And although no specific foods can heal diverticulosis, Dr. Ivanina says that increasing dietary fiber can help to prevent the development of new diverticula, diverticulitis, or diverticular bleeding.

Diverticulitis treatment is very nuanced, says Dr. Ivanina. “Immunocompetent, relatively healthy patients with uncomplicated diverticulitis who have no evidence of systemic inflammation can potentially be managed as outpatients,” she says.  

Most attacks of diverticulitis can be treated by bowel rest (a clear liquid diet) and a course of antibiotics, Dr. Morey says; these are the most common treatments. Commonly prescribed antibiotics for diverticulitis include:

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Surgery is considered when there is perforation of the diverticula due to severe active inflammation, says Dr. Morey, adding that if you develop an abscess, it needs to be evaluated.  Surgery may also be necessary If multiple, uncomplicated flares of diverticulitis occur, adds Dr. Rao—in that case, your surgeon may discuss resection (removal) of the affected area, says Dr. Rao. Dr. Ivanina emphasizes that surgery is an individualized decision that must be made between a patient and their colorectal or general surgeon. 

Diverticulosis vs. diverticulitis prevention

Diverticulosis is a common condition in older adults, with prevalence increasing over time, says Dr. Rao. And there are many modifiable risk factors that contribute to the development of diverticular disease, says Dr. Ivanina. These include being overweight or obese, low physical activity, smoking, and NSAID use. 

Diet, lifestyle, and genetic factors all influence the development of diverticular disease, says Dr. Rao. “A high-fiber diet that is plant based, adequate water intake, and daily activity will help with gut motility (the movement of food through the digestive tract),” she says. Patients with normal gut motility are less likely to develop diverticula and diverticular disease.

RELATED: The best diet for diverticulitis

If you’re having trouble getting enough fiber in your diet, a fiber supplement can help. Probiotics may also help with diverticulitis by improving gut health, although more research is needed.

Contact your healthcare provider or gastroenterologist if you are experiencing acute symptoms of diverticulitis such as abdominal pain, nausea, vomiting, a change in bowel movements, or rectal bleeding, Dr. Ivanina recommends.