Topics covered in this article
- What is diverticulitis?
- Diverticulosis and diverticulitis: what is the difference?
- Why do diverticula form?
- Causes and risk factors
- Symptoms of diverticulitis
- Warning signs and when to seek urgent care
- Diagnosis and tests
- Uncomplicated and complicated diverticulitis
- Treatment of diverticulitis
- Diet during and after diverticulitis
- Does every case need antibiotics?
- Possible complications
- Is colonoscopy needed afterward?
- How to reduce the risk of future episodes
- Myths and facts
- Quick FAQ
- Important disclaimer
- References and further reading
What is diverticulitis?
Diverticulitis is inflammation, and in some cases infection, of diverticula in the intestine.
Diverticula are small pouches or bulges that can form in the wall of the intestine, especially in the colon, which is the final part of the large intestine.
When these pouches are present but do not cause inflammation or significant symptoms, the condition is called diverticulosis.
When one or more diverticula become inflamed, the condition is called diverticulitis.
Diverticulitis can cause abdominal pain, fever, changes in bowel habits, nausea, and general discomfort. In some cases, it can lead to complications such as abscess, bowel perforation, fistula, obstruction, or peritonitis.
Important: diverticulitis is not the same as colon cancer. However, some symptoms can overlap, which is why medical evaluation is important, especially in new, severe, or recurrent episodes.
Diverticulosis and diverticulitis: what is the difference?
The terms diverticulosis and diverticulitis sound similar, but they do not mean the same thing.
Diverticulosis
Diverticulosis means that diverticula are present in the colon.
It is very common, especially with increasing age, and many people discover it incidentally during tests such as colonoscopy or CT scan.
In most cases, diverticulosis causes no symptoms and does not require specific treatment beyond guidance on bowel habits and prevention of complications.
Diverticulitis
Diverticulitis occurs when a diverticulum becomes inflamed.
This inflammatory process may be mild and localized, but it can also be more intense and cause complications.
The condition usually requires medical evaluation, because treatment depends on severity, symptoms, complications, and the person’s overall health.
Practical summary:
- Diverticulosis: presence of diverticula.
- Diverticulitis: inflammation or infection of diverticula.
Why do diverticula form?
Diverticula form at points of relative weakness in the intestinal wall.
Over time, pressure inside the colon may favor small protrusions of the inner lining through weaker areas of the bowel wall.
This occurs most often in the sigmoid colon, a region located in the lower left side of the abdomen.
For this reason, diverticulitis pain often appears in the lower left abdomen, although this can vary depending on the location of the diverticula and individual anatomy.
The formation of diverticula is associated with factors such as age, dietary pattern, constipation, physical inactivity, obesity, and changes in bowel motility.
Important: having diverticula does not mean that a person will necessarily develop diverticulitis. Many people live with diverticulosis for years without inflammation.
Causes and risk factors
Diverticulitis occurs when one or more diverticula become inflamed.
The exact mechanism may involve microscopic obstruction, changes in the gut microbiome, increased local pressure, inflammation of the bowel wall, and other factors still being studied.
Several factors increase the likelihood of diverticulosis and diverticulitis episodes.
Main risk factors include:
- Older age.
- Known diverticulosis.
- Low-fiber diet.
- Chronic constipation.
- Physical inactivity.
- Obesity.
- Smoking.
- Frequent use of nonsteroidal anti-inflammatory drugs, such as ibuprofen, naproxen, and diclofenac.
- Use of corticosteroids or immunosuppressive medications in some patients.
- Conditions that reduce immune function.
- Family history of diverticular disease.
Diverticulitis is more common in adults and older adults, but it can also occur in younger people.
In younger patients, obesity, inactivity, smoking, and genetic factors may play an important role.
Important: risk factors increase probability, but they do not confirm the diagnosis. Confirmation depends on clinical evaluation and, in many cases, imaging tests.
Symptoms of diverticulitis
Symptoms of diverticulitis can range from mild to severe.
The most typical presentation is pain in the lower left side of the abdomen, but not every patient follows this exact pattern.
Possible symptoms include:
- Abdominal pain, usually in the lower left abdomen.
- Pain that may worsen when touching the abdomen or moving.
- Fever.
- Chills.
- Nausea.
- Vomiting.
- Loss of appetite.
- Constipation.
- Diarrhea.
- Abdominal bloating.
- Gas or intestinal discomfort.
- General malaise.
- Changes in bowel habits.
In some people, pain may be more diffuse or appear in another area of the abdomen.
This may happen because of anatomical differences, diverticula location, or the presence of complications.
Symptoms can also resemble other conditions, such as appendicitis, urinary tract infection, kidney stones, inflammatory bowel disease, gastroenteritis, irritable bowel syndrome, gynecological conditions, and other causes of abdominal pain.
Important: persistent, worsening, or fever-associated abdominal pain should be evaluated by a healthcare professional.
Warning signs and when to seek urgent care
Some signs may suggest more severe diverticulitis or complications.
Seek urgent medical care if there is:
- Severe or worsening abdominal pain.
- A rigid, very painful abdomen or pain that worsens with touch.
- High or persistent fever.
- Severe chills.
- Persistent vomiting.
- Inability to eat or drink fluids.
- Dizziness, fainting, or signs of low blood pressure.
- Confusion or excessive sleepiness.
- Significant intestinal bleeding.
- Inability to pass stool or gas with marked abdominal distention.
- Worsening symptoms despite treatment.
- Abdominal pain in a person who is immunosuppressed, older, pregnant, or living with serious medical conditions.
These signs do not confirm a complication by themselves, but they increase the need for prompt evaluation.
Important: bowel perforation, peritonitis, abscess, and sepsis are serious conditions and require immediate care.
Diagnosis and tests
The diagnosis of diverticulitis begins with medical history and physical examination.
The clinician evaluates pain location, intensity, duration, fever, bowel changes, medication use, associated illnesses, and previous episodes.
In many cases, additional tests are needed to confirm the diagnosis and assess severity.
Blood tests
Blood tests may help identify signs of inflammation or infection.
Tests may include:
- Complete blood count.
- C-reactive protein.
- Kidney function tests.
- Electrolytes.
- Other tests depending on the clinical situation.
These tests help with assessment, but they do not confirm diverticulitis on their own.
Urine test
A urine test may help distinguish diverticulitis from urinary tract infection or kidney stones, especially when there is lower abdominal pain or urinary symptoms.
Computed tomography
Abdominal computed tomography, often with contrast when appropriate, is one of the main tests used to confirm diverticulitis and identify complications.
CT scan may show:
- Inflammation around diverticula.
- Thickening of the bowel wall.
- Abscess.
- Perforation.
- Air outside the bowel.
- Obstruction.
- Other causes of abdominal pain.
Ultrasound
Ultrasound may be used in some settings, especially when CT is not available or when avoiding radiation is preferred.
However, it depends heavily on the examiner’s experience and may be limited by intestinal gas, obesity, or severe pain.
Colonoscopy
Colonoscopy is not usually performed during the acute phase of diverticulitis, especially when there is significant inflammation, because of the risk of worsening complications.
In some cases, colonoscopy may be recommended after recovery, mainly to rule out other diseases and evaluate the colon.
Important: not every abdominal pain requires a CT scan, but when diverticulitis is suspected, symptoms are intense, diagnosis is uncertain, or warning signs are present, imaging can be essential.
Uncomplicated and complicated diverticulitis
Diverticulitis is commonly classified as uncomplicated or complicated.
This classification helps guide treatment, antibiotic use, hospitalization, drainage, or surgery.
Uncomplicated diverticulitis
Uncomplicated diverticulitis occurs when inflammation is localized, without abscess, free perforation, fistula, obstruction, or peritonitis.
In many cases, it can be treated conservatively, with monitoring, temporary dietary adjustments, hydration, pain control, and antibiotics in selected situations.
Complicated diverticulitis
Complicated diverticulitis occurs when one or more complications are present.
Examples include:
- Abscess.
- Bowel perforation.
- Peritonitis.
- Fistula.
- Bowel obstruction.
- Sepsis.
In these cases, treatment may require hospitalization, intravenous antibiotics, abscess drainage, surgical evaluation, or emergency surgery.
Important: severity should not be assessed by pain intensity alone. Imaging findings, vital signs, age, immune status, and associated diseases also influence decisions.
Treatment of diverticulitis
Treatment depends on the severity of the episode, the presence of complications, the patient’s overall health, and the initial response to care.
The goals are to control inflammation, treat infection when present, relieve symptoms, prevent complications, and reduce the risk of recurrence.
Outpatient treatment
Mild cases without signs of complication in stable patients may be treated outside the hospital, provided there is appropriate follow-up.
Treatment may include:
- Relative rest.
- Adequate hydration.
- Temporary diet adjustments according to tolerance.
- Pain relievers recommended by a healthcare professional.
- Antibiotics in selected cases.
- Education about warning signs.
- Reassessment if symptoms worsen or fail to improve.
Hospital treatment
Hospitalization may be needed when symptoms are more severe, complications are present, or risk is higher.
Situations that may require hospitalization include:
- Severe pain.
- Persistent fever.
- Persistent vomiting.
- Dehydration.
- Inability to take oral medication.
- Suspected abscess or perforation.
- Immunosuppression.
- Older age with higher clinical risk.
- Important associated medical conditions.
- Failure of initial treatment at home.
In the hospital, treatment may include intravenous antibiotics, intravenous fluids, temporary bowel rest, pain control, repeated examinations, abscess drainage, and evaluation by a surgeon or colorectal specialist.
Surgery
Surgery is not needed in most cases of uncomplicated diverticulitis.
It may be indicated in specific situations, such as:
- Bowel perforation with peritonitis.
- Abscess that does not improve with medical treatment or drainage.
- Bowel obstruction.
- Fistula.
- Recurrent episodes with major impact on quality of life.
- Suspicion of cancer or inability to rule out another disease.
- Selected cases in immunosuppressed or higher-risk patients.
The decision to operate should be individualized.
The number of episodes alone is not the only criterion. Severity, complications, age, comorbidities, quality of life, and patient preferences also matter.
Diet during and after diverticulitis
Diet in diverticulitis depends on the phase of the condition.
During an acute flare, especially when pain, nausea, or significant inflammation is present, a clinician may recommend a lighter diet that is temporarily lower in residue.
During the acute phase
In mild cases, easily digestible foods may be recommended for a short time, advancing as symptoms improve.
In some cases, especially with more intense symptoms, a temporary liquid diet may be advised.
Options that may be used depending on guidance and tolerance include:
- Water.
- Clear broth.
- Clear teas.
- Gelatin.
- Strained juices, if tolerated.
- Light foods introduced gradually.
This phase should be temporary.
Very restrictive diets for many days can cause weakness, weight loss, and inadequate nutrient intake.
After improvement
After symptoms improve, foods are usually reintroduced gradually.
Long term, the goal is often a balanced, fiber-rich diet, unless there is an individual contraindication.
Sources of fiber include:
- Fruits.
- Vegetables.
- Legumes.
- Beans and other pulses.
- Oats.
- Whole grains.
- Seeds and nuts, if well tolerated.
Fiber intake should be increased gradually and with adequate hydration to reduce gas, bloating, and discomfort.
Important: the best diet varies depending on disease phase, symptoms, bowel history, and medical or nutritional guidance.
Does every case need antibiotics?
For many years, almost all cases of diverticulitis were treated with antibiotics.
Today, in many guidelines, selected cases of mild acute uncomplicated diverticulitis in stable patients may be managed without antibiotics, as long as there is appropriate medical evaluation and follow-up.
This does not mean antibiotics are no longer important.
Antibiotics are still indicated in many situations, such as:
- Complicated diverticulitis.
- Abscess.
- Suspected or confirmed perforation.
- Persistent fever or significant systemic signs.
- Immunosuppression.
- Relevant comorbidities.
- More intense or progressive symptoms.
- Failure to improve with initial measures.
The decision must be individualized.
Unnecessary antibiotic use can increase side effects and antimicrobial resistance. On the other hand, not using antibiotics when they are indicated can increase the risk of complications.
Important: do not take antibiotics on your own for abdominal pain. The diagnosis must be clear, and treatment choice should consider severity and individual risks.
Possible complications
Most cases of diverticulitis improve with appropriate treatment, but complications can occur.
Main complications include:
- Abscess: a collection of pus near the inflamed bowel.
- Bowel perforation: an opening in the intestinal wall, allowing intestinal contents to leak.
- Peritonitis: severe inflammation of the membrane lining the abdomen.
- Fistula: an abnormal connection between the intestine and another organ, such as the bladder, vagina, or skin.
- Bowel obstruction: partial or complete blockage of intestinal passage.
- Bleeding: more common in diverticular disease than in diverticulitis itself, but it may occur.
- Recurrence: new episodes of diverticulitis over time.
- Sepsis: a severe body-wide response to infection.
Complications require more intensive treatment and, in some cases, radiological intervention or surgery.
Important: worsening pain, persistent fever, vomiting, poor general condition, marked abdominal distention, or confusion requires urgent evaluation.
Is colonoscopy needed afterward?
Colonoscopy may be recommended after recovery from an episode of diverticulitis, especially if it is the first episode, symptoms are atypical, the person has not had a recent high-quality colonoscopy, or there is a need to rule out other diseases.
The test is generally not performed during the acute phase, because the bowel is inflamed and there may be a higher risk of complications.
The ideal timing should be defined by the healthcare professional, often several weeks after the episode has resolved.
Colonoscopy may help evaluate:
- Presence of diverticula.
- Polyps.
- Signs of inflammatory bowel disease.
- Suspicious lesions.
- Colorectal cancer, when it must be ruled out.
Important: the indication for colonoscopy after diverticulitis depends on age, medical history, previous exams, CT findings, episode severity, and risk factors.
How to reduce the risk of future episodes
It is not always possible to completely prevent future episodes of diverticulitis.
However, some measures may help reduce risk and improve intestinal health.
Important measures include:
- Gradually increase fiber intake after recovery, when allowed.
- Maintain good hydration.
- Avoid chronic constipation.
- Exercise regularly.
- Maintain a healthy weight.
- Do not smoke.
- Avoid frequent use of anti-inflammatory medications unless medically advised.
- Control associated conditions, such as diabetes, when present.
- Avoid self-medication.
- Keep medical follow-up in recurrent cases.
The use of probiotics, supplements, rifaximin, or other preventive strategies should be discussed individually, because indications vary and benefit is not clear for every patient.
Important: prevention does not mean following a permanently restrictive diet. In many cases, the goal is a balanced, fiber-rich diet with good hydration and healthy habits.
Myths and facts
“Diverticulosis and diverticulitis are the same thing.”
Myth.
“Diverticulosis means diverticula are present in the intestine.”
Fact.
“Diverticulitis is inflammation or infection of diverticula.”
Fact.
“Everyone with diverticula will develop diverticulitis.”
Myth.
“Pain in the lower left abdomen can happen in diverticulitis.”
Fact.
“Every case of diverticulitis requires surgery.”
Myth.
“Some mild, uncomplicated cases may be treated without antibiotics, with appropriate medical evaluation.”
Fact.
“People with diverticulosis must always avoid seeds, corn, popcorn, and nuts.”
Myth.
“Fever, worsening pain, and a rigid abdomen are warning signs.”
Fact.
Quick FAQ
Can diverticulitis be cured?
An episode of diverticulitis can resolve completely with appropriate treatment. However, some people may have new episodes later in life.
Is diverticulitis serious?
It can be mild or severe. Uncomplicated cases often improve well, but complicated diverticulitis may require hospitalization, drainage, or surgery.
What is the typical pain of diverticulitis?
The most typical pain is in the lower left abdomen, but it can vary. The pain is often persistent and may be associated with fever, nausea, or bowel changes.
Can diverticulitis cause diarrhea?
Yes. Although many people have constipation, diverticulitis can also cause diarrhea or alternating bowel habits.
Can diverticulitis turn into cancer?
Diverticulitis is not cancer. However, some symptoms may resemble colorectal cancer, and in some cases colonoscopy after recovery may be recommended to rule out other diseases.
Does everyone who had diverticulitis need part of the colon removed?
No. Surgery is reserved for complicated cases, selected recurrent cases, or specific situations. The decision should be individualized.
Can I eat popcorn, seeds, and nuts if I have diverticula?
Automatic restriction of these foods is no longer recommended for everyone. Many people can eat them if they tolerate them well. Guidance should be individualized.
What should I eat during a flare?
During the acute phase, it may be necessary to temporarily reduce fiber load and use a liquid or light diet according to medical guidance. After improvement, foods are usually reintroduced gradually.
Are antibiotics always necessary?
Not necessarily. Some mild, uncomplicated cases may be monitored without antibiotics, but this decision should be made by a healthcare professional. Severe, complicated, or higher-risk cases usually require antibiotics.
When should I go to the emergency department?
Seek urgent care if there is severe pain, high fever, persistent vomiting, a rigid abdomen, dizziness, fainting, confusion, rapid worsening, significant bleeding, or inability to pass stool and gas.
Important disclaimer
This content is for educational purposes only and does not replace professional medical evaluation. Persistent, severe, or worsening abdominal pain, fever, vomiting, a rigid abdomen, marked distention, intestinal bleeding, fainting, confusion, worsening general condition, or suspected complication should be evaluated by a healthcare professional. Do not use antibiotics, anti-inflammatory medications, or laxatives on your own to treat abdominal pain without medical guidance.
References and further reading
- American Gastroenterological Association (AGA). Clinical practice update on medical management of colonic diverticulitis.
- American Society of Colon and Rectal Surgeons (ASCRS). Clinical practice guidelines for the treatment of left-sided colonic diverticulitis.
- World Society of Emergency Surgery (WSES). Guidelines for the management of acute colonic diverticulitis in the emergency setting.
- National Institute for Health and Care Excellence (NICE). Diverticular disease: diagnosis and management.
- National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK). Diverticulosis and diverticulitis.
- Mayo Clinic. Diverticulitis: symptoms and causes.
- Cleveland Clinic. Diverticulitis: symptoms, causes, diagnosis, and treatment.
- Merck Manual Professional Version. Colonic diverticulosis and diverticulitis.
