Diverticulitis

What is diverticulitis?

Diverticulitis is inflammation or infection of small pouches, called diverticula, that can form in the wall of the large intestine (colon). A single pouch is called a diverticulum. Many people develop these pouches as they get older without ever knowing it — the simple presence of pouches without inflammation is called diverticulosis, and it usually causes no symptoms. Diverticulitis happens when one or more of these pouches becomes inflamed or infected, which can cause pain, fever, and changes in bowel habits.

Understanding what is diverticulitis starts with understanding the difference between these two related conditions. Diverticulosis is very common, especially in people over 60, and most people who have it never develop problems. Diverticulitis is the complication that occurs in a smaller share of those people, and it can range from a mild episode that settles with rest and simple measures to a serious illness that needs hospital care or surgery.

Diverticulitis becomes more common with age, but it can also occur in younger adults. It affects both men and women. In Western countries, the pouches most often form in the lower left part of the colon, called the sigmoid colon, which is why pain from diverticulitis is often felt in the lower left side of the abdomen. In some parts of Asia, pouches more often form on the right side of the colon, so the pain pattern can differ.

Symptoms of diverticulitis

Diverticulitis symptoms can appear gradually over a few days or come on more suddenly. The most common symptoms include:

• Abdominal pain — usually constant and most often in the lower left side of the belly, though it can occur on the right side in some people. The pain may worsen with movement.
• Fever and chills — a sign that the body is responding to inflammation or infection.
• Nausea or vomiting — sometimes with a reduced appetite.
• Changes in bowel habits — constipation is common; some people have diarrhea instead.
• Bloating and abdominal tenderness — the belly may feel sore when pressed.
• Urinary symptoms — in some cases, inflammation near the bladder can cause a frequent or urgent need to urinate.

Doctors often describe diverticulitis as either uncomplicated or complicated, and the symptoms can differ between these forms. In uncomplicated diverticulitis, the inflammation stays limited to the wall of the colon and the tissue immediately around it. Symptoms are usually localized pain, low-grade fever, and mild changes in bowel habits. Many people with uncomplicated diverticulitis can be treated without staying in the hospital.

In complicated diverticulitis, the inflammation leads to further problems. These can include an abscess (a pocket of pus next to the colon), a perforation (a hole in the colon wall that lets intestinal contents leak into the abdomen), peritonitis (widespread inflammation of the lining of the abdomen, which is a medical emergency), a fistula (an abnormal connection between the colon and another organ such as the bladder), or a bowel obstruction (a blockage of the intestine caused by swelling or scarring). Symptoms of complicated diverticulitis tend to be more severe: high fever, intense or spreading abdominal pain, a rigid or very tender abdomen, inability to pass stool or gas, or feeling very unwell. These signs need urgent medical attention.

Some people also experience repeated episodes over time. After a first attack, later episodes may feel similar, but each one should still be assessed by a doctor, because complications can develop at any stage.

Causes and risk factors

The pouches of diverticulosis are thought to form when weaker spots in the colon wall bulge outward under pressure. Diverticulitis causes are not fully understood, but current thinking is that a pouch becomes inflamed when its opening is blocked or its thin wall is injured, allowing bacteria that normally live in the colon to cause local inflammation or infection. Older explanations blamed seeds, nuts, and popcorn getting trapped in the pouches, but research has not supported this idea, and most doctors no longer advise avoiding these foods.

Several factors are associated with a higher risk of developing diverticula and diverticulitis:

• Older age — the colon wall changes with age, and pouches become more common over time.
• A low-fiber diet — diets low in fruits, vegetables, and whole grains are linked with diverticular disease, possibly because low fiber leads to harder stools and higher pressure inside the colon.
• Obesity — carrying excess weight is associated with a higher risk of diverticulitis and its complications.
• Physical inactivity — regular exercise appears to lower risk.
• Smoking — smokers have a higher risk of diverticulitis and complications than non-smokers.
• Certain medications — regular use of nonsteroidal anti-inflammatory drugs (NSAIDs, a common class of pain relievers such as ibuprofen), steroids, and opioids has been linked with a higher risk of diverticulitis and perforation.
• Family history and genetics — diverticular disease can run in families, suggesting inherited factors play a role.

Having one or more risk factors does not mean a person will definitely develop diverticulitis, and some people develop it without any obvious risk factors. Constipation and straining have also been discussed as contributors, although the evidence is mixed.

Diagnosis

Diverticulitis diagnosis usually begins with a conversation about your symptoms and a physical examination. The doctor will ask where the pain is, when it started, and whether you have fever, nausea, or changes in your bowel habits, and will gently press on your abdomen to check for tenderness. Because other conditions — such as appendicitis, irritable bowel syndrome, inflammatory bowel disease, urinary infections, gynecological problems, and, less commonly, colon cancer — can cause similar symptoms, doctors typically use tests to confirm the diagnosis rather than relying on symptoms alone.

Common steps in diagnosing diverticulitis include:

• Blood tests — to look for signs of inflammation or infection, such as a raised white blood cell count or elevated inflammatory markers.
• Urine tests — to rule out a urinary tract infection, which can cause similar lower abdominal symptoms.
• CT scan (computed tomography) — a detailed X-ray-based scan of the abdomen and pelvis. This is the most reliable imaging test for diverticulitis. It can confirm inflammation around a diverticulum, show how severe the episode is, and detect complications such as an abscess or perforation.
• Ultrasound or MRI — sometimes used as alternatives, for example in pregnant patients or when radiation exposure should be avoided.
• Pregnancy test — often performed in women of childbearing age to exclude pregnancy-related causes of pain.

A colonoscopy — an examination of the inside of the colon using a thin, flexible tube with a camera — is generally not performed during an acute attack, because inserting the instrument into an inflamed colon carries a small risk of injury. However, doctors often recommend a colonoscopy several weeks after the episode has settled, particularly after a first or complicated attack, to examine the colon thoroughly and rule out other conditions such as colorectal cancer. You can read more about this procedure on the endoscopy and colonoscopy page.

Treatment options

Diverticulitis treatment depends on how severe the episode is, whether complications are present, and your overall health. There is no single approach that fits everyone, and your doctor will tailor the plan to your situation. An overview of the condition and its management is also available on the diverticulitis treatment page.

Watchful waiting and supportive care

Mild, uncomplicated diverticulitis can often be managed at home. Supportive care may include rest, a temporary liquid or low-fiber diet to give the bowel a chance to settle, and simple pain relief as advised by your doctor (acetaminophen, also called paracetamol, is often preferred over NSAIDs, which may irritate the gut). As symptoms improve, fiber is gradually reintroduced. Follow-up is important to confirm that the episode is resolving as expected.

Antibiotics

Antibiotics — medicines that fight bacterial infection — have traditionally been a standard part of treatment. In recent years, research has suggested that many people with mild, uncomplicated diverticulitis recover without antibiotics, and guidelines in several countries now allow doctors to use them selectively rather than automatically. Antibiotics are still generally recommended for people with more severe episodes, complicated disease, weakened immune systems, or other significant health problems. Whether you need antibiotics is a decision for your treating doctor based on your individual situation.

Hospital treatment

People with severe pain, high fever, vomiting that prevents drinking, complications, or other health conditions that make an episode riskier may need hospital admission. In the hospital, treatment can include intravenous fluids (fluids given through a vein), intravenous antibiotics, and resting the bowel by limiting food temporarily.

Drainage of an abscess

If a CT scan shows an abscess — a collected pocket of pus — larger abscesses are often treated by percutaneous drainage. In this procedure, a radiologist uses imaging guidance to place a thin tube through the skin into the abscess so the pus can drain, usually alongside antibiotic treatment. Smaller abscesses may respond to antibiotics alone.

Surgery

Surgery is not needed for most episodes of diverticulitis, but it may be recommended in certain situations:

• Emergency surgery — for perforation with peritonitis, uncontrolled infection, or a blockage that does not resolve. The surgeon typically removes the affected segment of colon. In some emergency operations, a temporary colostomy is created — an opening in the abdominal wall through which stool passes into a bag — which can often be reversed in a later operation.
• Planned (elective) surgery — sometimes considered for people with repeated attacks that significantly affect their quality of life, ongoing complications such as a fistula or narrowing of the bowel, or other individual factors. Modern practice weighs the risks and benefits case by case rather than recommending surgery after a fixed number of attacks. Many elective operations can be performed laparoscopically, meaning through small incisions using a camera.

Diverticulitis is usually managed by specialists in digestive diseases, with surgeons involved when procedures are needed. At Acibadem, this condition falls under the gastroenterology department, which works together with colorectal surgery when required.

Living with diverticulitis and outlook

For most people, the outlook after an episode of diverticulitis is good. Many people recover fully from a first uncomplicated attack and never have another one. Others experience repeat episodes, and a smaller group develops complications or ongoing symptoms. It is not possible to predict with certainty who will have further attacks, but complications are more likely with severe first episodes, smoking, obesity, and certain medications.

After recovery, doctors often suggest lifestyle measures that may lower the chance of future episodes, although no measure can guarantee prevention:

• Eat a fiber-rich diet — fruits, vegetables, whole grains, and legumes help keep stools soft and reduce pressure in the colon. Fiber should be increased gradually, with plenty of fluids.
• Stay physically active — regular exercise is associated with a lower risk of diverticulitis.
• Maintain a healthy weight — this may reduce the risk of both attacks and complications.
• Avoid smoking — quitting benefits the bowel as well as overall health.
• Review medications with your doctor — especially regular NSAID use, if there is a safe alternative for you.

Contrary to older advice, most guidelines no longer recommend avoiding nuts, seeds, corn, or popcorn, as studies have not shown these foods trigger attacks. If you notice that certain foods reliably worsen your symptoms, it is reasonable to discuss this with your doctor or a dietitian rather than restricting your diet on your own.

Some people continue to have mild, intermittent abdominal discomfort or bloating after an attack, sometimes described as symptomatic uncomplicated diverticular disease. If ongoing symptoms affect your daily life, follow-up with a gastroenterologist can help clarify the cause and guide management.

Frequently asked questions

What is the difference between diverticulosis and diverticulitis?

Diverticulosis means small pouches (diverticula) are present in the colon wall but are not inflamed; it is very common with age and usually causes no symptoms. Diverticulitis means one or more of those pouches has become inflamed or infected, causing pain, fever, or other symptoms. Most people with diverticulosis never develop diverticulitis, but the pouches are the starting point for it.

What do diverticulitis symptoms feel like?

Most people describe a constant pain in the lower abdomen, often on the left side, that may be accompanied by fever, nausea, bloating, and constipation or diarrhea. The pain can build over several days or start more suddenly. Because similar symptoms occur in other conditions, only a medical assessment — usually including a scan — can confirm whether the cause is diverticulitis.

Can diverticulitis heal on its own?

Mild, uncomplicated episodes often settle with rest, a temporary adjusted diet, and simple pain relief, sometimes without antibiotics. However, this should happen under a doctor’s guidance, because complications such as an abscess or perforation are not always obvious at the start. Worsening pain, high fever, or inability to eat and drink means the episode may not be resolving on its own.

How serious is diverticulitis?

Severity varies widely. Many episodes are mild and treated at home. A minority of cases become complicated — with abscesses, perforation, fistulas, or bowel obstruction — and these can be serious, sometimes requiring hospital care, drainage procedures, or surgery. Peritonitis from a perforated colon is a medical emergency. This range is why every suspected episode deserves medical evaluation, even if previous attacks were mild.

How is diverticulitis diagnosed?

Doctors typically combine a physical examination with blood tests and imaging. A CT scan of the abdomen is the most reliable way to confirm diverticulitis and to check for complications. A colonoscopy is usually avoided during an acute attack but is often recommended some weeks later, especially after a first or complicated episode, to examine the colon fully and rule out other conditions.

What foods should I avoid with diverticulitis?

During an acute attack, your doctor may suggest a short period of clear liquids or low-fiber foods while the inflammation settles. Once recovered, most people are advised to eat a high-fiber diet rather than a restrictive one. The old advice to avoid nuts, seeds, and popcorn is no longer supported by evidence, though individual tolerance varies and any personal triggers can be discussed with your care team.

How long does recovery from diverticulitis take?

Recovery time depends on the severity of the episode. Symptoms of mild diverticulitis often improve within a few days of starting treatment, with full recovery over one to two weeks in many cases. Complicated episodes, hospital stays, or surgery involve longer recovery periods. Your doctor can give you a more realistic timeline based on your specific situation and how you respond to treatment.

When to see a doctor

See a doctor promptly if you develop persistent abdominal pain, especially with fever or a change in your bowel habits, or if symptoms of a previous episode return. Do not try to self-diagnose or self-treat abdominal pain that lasts more than a day or two, because several serious conditions can feel similar.

Seek urgent medical care — go to an emergency department — if you experience any of the following red-flag warning signs:

• Severe or rapidly worsening abdominal pain, or pain that spreads across the whole abdomen
• A hard, rigid, or extremely tender abdomen
• High fever with chills or shaking
• Persistent vomiting or inability to keep fluids down
• Inability to pass stool or gas, especially with a swollen abdomen
• Rectal bleeding, particularly if it is heavy or ongoing
• Signs of serious illness such as confusion, dizziness, a racing heartbeat, or fainting

These symptoms can indicate complications such as perforation, peritonitis, abscess, or significant bleeding, all of which need urgent assessment. If you have been diagnosed with diverticular disease before, mention this when you seek care, as it helps doctors evaluate your symptoms more quickly.