Diverticulitis refers to inflammation of the diverticula, which are small pouches that form in the colon lining. Ulcerative colitis (UC) is an inflammatory bowel disease (IBD) where people develop inflammation and ulcers in the lining of the large intestine.

In this article, we compare symptoms, diagnosis, treatment, complications, and outlook of both conditions.

A person holding their stomach who may have ulcerative colitis or diverticulitis.Share on Pinterest
Javier Pardina/Stocksy

Small pouches called diverticula can form in the colon lining and push out through weak spots in the outer wall of the colon. If a person has diverticula in their colon, they have what health experts refer to as diverticulosis.

Diverticulitis is a condition where the diverticula become inflamed. Around 10–25% of individuals with diverticulosis may have diverticulitis.

People may also use the term “diverticular disease” for diverticulitis or diverticular bleeding or if diverticula cause chronic symptoms.

UC is an IBD where an overreactive immune system causes inflammation and ulcers to develop in the lining of the large intestine.

UC is a chronic condition, and people may go through periods of remission, when they experience no symptoms of UC.

In the table below, we compare the two conditions:

DiverticulitisUC
DefinitionDiverticulitis is a condition where small pouches form in the intestinal lining and become inflamed.UC is a type of IBD where an overactive immune response causes inflammation and ulcers in the intestinal lining.
Symptoms Symptoms can include:
abdominal pain on one side
constipation
diarrhea
nausea
vomiting
fever
chills
rectal bleeding
Symptoms can include:
• diarrhea
• an urgent need for bowel movements
blood or mucus in stool
• abdominal pain and cramping
CausesThere is no known cause, but the following may play a part:
• genetics
• diet low in fiber and high in red meat
• immune system problems
• changes in the microbiome
• bacteria trapped in the diverticula
There is no known cause, but the following may play a role:
• genetics
• unusual immune system reactions
• microbiomes in the digestive tract
• environmental factors
TriggersLow fiber consumption and high red meat intake may increase the risk of diverticulitis and complications.Certain foods, such as spicy foods, lactose, and sugary foods, may trigger UC flares.
TreatmentTreatment options include:
antibiotics
• a temporary clear liquid diet
• pain relief medication
• surgery to remove part of the colon, in some cases
Treatment can include medications to reduce inflammation, and, in some cases, surgery to remove the colon and rectum.
Cancer riskThere may be a slightly increased risk of colorectal cancer, with older adults and those with complicated diverticulitis being at higher risk.There is an increased risk of developing colorectal cancer.
ComplicationsComplications can include:
• pelvic abscess
• intestinal perforation
• fistulas
• peritonitis
bowel obstruction
sepsis
• rectal bleeding
Complications can include:
• rectal bleeding
iron deficiency anemia
• expansion or tears in the colon
blood clots
primary sclerosing cholangitis (PSC)
• toxic megacolon
• intestinal perforation
OutlookThe outlook depends on a person’s age and overall health and the severity of diverticulitis. Treatment may result in none to mild symptoms in two-thirds of people.UC requires long-term management. Treatment can help people maintain remission and live a relatively normal life.

In the sections below, we outline the symptoms of diverticulitis and UC.

Diverticulitis

Symptoms of diverticulitis may include:

  • abdominal pain
  • constipation or diarrhea
  • fever
  • chills
  • nausea or vomiting
  • increased urgency, frequency, or discomfort when urinating, if an inflamed part of the colon comes into contact with the wall of the bladder
  • rectal bleeding

People with diverticulitis usually experience severe and sudden abdominal pain, but they may also have mild pain that worsens over several days. The pain may be constant or come and go. Also, over time, the pain intensity may vary.

UC

Symptoms of UC can be mild to severe and can include:

  • persistent diarrhea
  • rectal bleeding or blood in stool
  • cramping or abdominal pain
  • mucus or pus in stool
  • an urgent need to have a bowel movement
  • a persistent urge to have a bowel movement, even if bowels are empty

UC symptoms can come on suddenly or start gradually and then worsen over time.

Most people with UC have flares, which is when symptoms are present, and periods of remission, which is when no symptoms occur. Remission may last for weeks or years.

Healthcare professionals do not know the exact cause of either condition. However, they are aware of factors that can increase the likelihood of developing diverticulitis or UC.

Diverticulitis

There is no known cause of diverticulitis. Certain factors, however, may increase the risk of diverticular disease or cause its development. These include:

  • genetics
  • stool or bacteria becoming trapped in a pouch in the colon
  • a change to the microbiome in the intestines
  • issues with muscles, nerves, or connective tissue in the colon
  • issues with the immune system

Lifestyle factors may also play a role, including:

Diverticulitis affects both males and females. It is more common in males under the age of 50 years and in females aged 50–70 years. In people over 70 years, diverticulitis is more common in females.

UC

Health experts do not know the exact cause of UC. They think, however, that the following may play a role:

  • Genetics: UC can run in families, so having certain genes may increase the risk of developing UC.
  • Overactive immune system: The immune system creates temporary inflammation to help protect and heal the body from infection or illness. With UC, inflammation continues for longer than necessary, leading to chronic inflammation and ulcers in the intestinal lining.
  • Microbiome: There may be differences between the microbiomes in the digestive tract of people with IBD and individuals without IBD.
  • Environment: External factors and surroundings may affect a person’s genes, immune system, and microbiome, potentially playing a role in IBD.

People with UC or diverticulitis need to be careful about their dietary choices.

Diverticulitis

According to the National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK), a diet low in fiber and high in red meat may increase the risk of diverticulitis.

Consuming more fiber and reducing red meat intake may lower the risk of diverticulitis and complications.

There is no evidence to suggest a link between eating nuts, seeds, or popcorn and an increased risk of diverticulitis or diverticular bleeding.

Learn more about the best foods for diverticulitis here.

UC

People may find that certain foods can trigger or worsen symptoms of UC.

Although different for each person, the following foods may trigger symptoms in some individuals:

  • insoluble fiber, such as raw cruciferous vegetables, whole nuts, and whole grains
  • lactose
  • sugary foods
  • high fat, fried, or greasy foods
  • alcohol and caffeine
  • spicy foods

Learn more about foods to eat and avoid with UC here.

Healthcare professionals may recommend the following treatment options:

Diverticulitis

Treatment for diverticulitis may include:

  • antibiotics
  • a temporary clear liquid diet, to allow the colon to rest
  • pain relief medication, such as acetaminophen

In severe cases, people may require surgery to remove a section of the colon.

UC

Treatment for UC may include long-term use of medications to control inflammation, such as:

A person may require surgery to remove the colon and rectum if their symptoms do not improve or if they have colorectal cancer or any serious complications.

Surgeons may also perform an ileostomy. They will attach the end of the ileum, which is a part of the small intestine, to an opening in the abdomen called a stoma. This allows the body to store and remove stools in an alternative way.

To diagnose each of the two conditions, doctors may carry out a physical examination and order the following:

A healthcare professional may order a colonoscopy to help diagnose diverticulitis and an endoscopy to diagnose UC.

Diverticulitis and UC can cause the following complications:

Diverticulitis

Complications of diverticulitis may include:

  • a pelvic abscess, when an infection causes a pus-filled pocket in the pelvic area
  • an intestinal perforation, which is a hole in the wall of the intestine
  • a fistula, which is an abnormal opening that allows contents to leak out
  • peritonitis, an infection in the lining of the abdomen
  • a blockage in the intestines
  • sepsis
  • rectal bleeding

According to a 2020 meta-analysis, there is a small risk of colorectal cancer with diverticulitis. Older adults and those with complicated diverticulitis have a higher risk of developing this type of cancer.

UC

Complications of UC may include:

  • rectal bleeding
  • iron deficiency anemia
  • expansion or tears in the colon
  • blood clots
  • PSC

Moreover, toxic megacolon and perforation are potential complications that may warrant emergency surgery and colectomy.

In long-term cases of UC, there is an increased risk of precancerous changes and colorectal cancer. PSC can also increase the risk of bile duct cancer.

People can take the following steps to help prevent UC and diverticulitis from developing:

Diverticulitis

Factors that may help lower the risk of developing diverticulitis include:

  • eating a diet high in fiber and low in red meat
  • engaging in regular physical activity
  • avoiding smoking
  • reaching or maintaining a moderate body weight

If people have diverticulitis without any complications, a doctor may suggest surgery to remove part of the colon to prevent diverticulitis from reoccurring.

UC

Preventive measures for UC include:

The outlook for each condition can depend on a variety of factors.

Diverticulitis

The outlook for people with diverticulitis can depend on a range of factors, including:

  • severity of the condition
  • a person’s age and overall health
  • any coexisting conditions

Most people with uncomplicated diverticulitis will have a positive response to treatment. Around 15% of people may require surgery to treat diverticulitis. After successful treatment, one-third of people will not have any symptoms, one-third will experience mild symptoms, and one-third will have recurrent diverticulitis.

UC

UC is a chronic condition that a person will need to manage throughout their life.

Managing flare-ups and uncomfortable symptoms can be difficult for some individuals, but effective treatment can help people lead a relatively normal life.

By managing their condition, some individuals with UC may experience remission for weeks or even years.

Diverticulitis is a condition where small pouches form in the intestinal lining and become inflamed. UC is a type of IBD in which an overactive immune response causes inflammation and ulcers in the large intestine.

Medication and lifestyle factors can help manage both conditions, which in turn may help a person relieve symptoms or maintain remission.

In severe cases, people may require surgery to remove part of the colon or rectum.