Diverticulitis: Symptoms, Causes, Treatment & Diet — Complete Guide
Updated: 2 days ago
Medically reviewed by Dr. Baraa Alnahhal, MD · Last reviewed: October 2026
Quick Answer
Diverticulitis is inflammation or infection of small, bulging pouches (diverticula) in the wall of the colon. Its hallmark sign is sudden, intense lower left abdominal pain, often with nausea and fever. Mild cases are treated with rest, diet changes and possibly antibiotics, while severe cases need hospital care and sometimes surgery. A high-fiber diet helps prevent it.
What the research says
Eating nuts and popcorn did not increase diverticulitis risk. A prospective study of 47,228 US men followed for 18 years (801 diverticulitis cases) found that men who ate nuts at least twice a week had a hazard ratio of 0.80 for diverticulitis (95% CI 0.63–1.01) and men who ate popcorn at least twice a week had 0.72 (95% CI 0.56–0.92), compared with men who ate them less than once a month; corn showed no association, and the authors concluded that the advice to avoid these foods should be reconsidered. (Strate et al., JAMA, 2008) [3]
A healthy lifestyle was linked to about half the risk of diverticulitis. In an analysis of three large US cohorts (179,564 participants) using a lifestyle score built from smoking, body mass index, physical activity, fiber, and red meat, people with the healthiest score (5) had a hazard ratio of 0.50 for diverticulitis (95% CI 0.44–0.57) compared with a score of 0, and the benefit held across low, mid, and high genetic-risk groups. (Ma et al., Gut, 2025) [4]
At a Glance
Topic | Key Facts |
What it is | Inflammation or infection of pouches (diverticula) in the colon wall |
Diverticulosis vs. diverticulitis | Pouches without inflammation (usually symptom-free) vs. pouches that are inflamed or infected |
Main signs | Sudden, intense lower-left belly pain; nausea; fever; tenderness; diarrhea or constipation |
Who is most at risk | Over 50; obesity; smoking; low-fiber or high red-meat diet; heavy alcohol; inactivity; low vitamin D; steroids, opioids, NSAIDs |
How it's confirmed | Physical exam, blood/urine/stool tests, and CT scan |
Complications | Affect about 15% — abscess, colon blockage, fistula, peritonitis, bleeding |
Main treatments | Rest and diet changes, antibiotics, IV antibiotics in hospital, surgery when needed |
Prevention | High-fiber diet, fluids, regular exercise, healthy weight, quit smoking, limit alcohol |
What Is Diverticulitis?
Diverticulosis occurs when small, bulging pouches — called diverticula (a single one is a diverticulum) — develop in the wall of the digestive tract. The wall of the large intestine, or colon, is normally smooth, and these irregular pouches usually form in the lower part of the colon.
The presence of diverticula is called diverticulosis — and it is not a disease condition. Diverticula are common, especially after age 50, and most often they don't cause problems.
When one or more of these pouches become inflamed or infected, the condition is called diverticulitis. Inflammation is the immune system's activity that increases blood flow and fluids to a site in the body and delivers disease-fighting cells.
Inflammation of diverticula can cause severe pain, fever, nausea, and changes in your stool habits.
Treatment depends on severity: mild diverticulitis is usually treated with rest, diet changes, and possibly antibiotics, while severe diverticulitis usually needs antibiotic treatment in the hospital. Surgery may be needed for severe or frequent diverticulitis.
Signs and Symptoms
The most common symptom of diverticulitis is pain in the abdomen — the area below the chest. Most often, the pain is in the lower left abdomen, and it is usually sudden and intense. Pain may start mild and gradually worsen, or its intensity may vary over time.
Symptom | What you may notice |
Abdominal pain | Usually lower left; sudden and intense, or mild and worsening |
Nausea | Queasiness, sometimes with vomiting |
Fever | Elevated body temperature |
Abdominal tenderness | Belly hurts when touched |
Stool changes | Sudden diarrhea or constipation |
When to see a doctor: Get medical care anytime you have constant, unexplained abdominal pain, particularly if you also have a fever and notable changes in stools.
What Causes Diverticulitis?
Diverticula gradually develop over time in the walls of the colon and are common in older adults. Pressure in the colon — possibly from spasms or straining — may cause pouches to form where the colon wall is weak.
Diverticulitis is the inflammation of one or more of these diverticula. This may happen because of bacterial disease or damage to the tissues of the diverticula.
Risk Factors
Diverticulitis is more common among people over 50. Other factors that increase the risk include:
Risk factor | Details |
Age over 50 | Risk rises with age |
Obesity | Extra body weight raises risk |
Smoking | Associated with increased risk |
Low-fiber diet | Weakens stool bulk and movement |
Diet high in red meat | Increases risk |
Heavy alcohol use | Increases risk |
Lack of exercise | Inactivity raises risk |
Low vitamin D levels | Associated with increased risk |
Certain medicines | Steroids, opioids, and NSAIDs such as ibuprofen (Advil, Motrin IB) and naproxen sodium (Aleve) |
Complications
About 15 percent of people with diverticulitis develop complications:
Abscess — a pocket of pus from bacterial disease
Blockage of the colon
Fistula — an irregular passageway between the bowel and another organ in the body
Peritonitis — a tear in the colon wall that lets waste spill out, causing serious disease of the abdomen lining
Diverticular hemorrhage — bleeding from ruptured blood vessels
Prevention
Five habits can help prevent diverticulitis:
Exercise regularly. Regular, vigorous exercise decreases the risk of diverticulitis.
Eat a high-fiber diet. High-fiber foods — fruits, vegetables, whole grains, seeds, and beans — improve the movement of waste through the colon and decrease risk. Cut back on red meats and sweets.
Maintain a healthy weight. Talk to your healthcare professional or a dietitian about weight goals and strategies to reach them.
Drink plenty of fluids. Fiber works by absorbing water and increasing soft, bulky waste; fluids improve waste movement and prevent constipation.
Quit smoking and limit alcohol use. Both are associated with an increased risk.
An important update on old advice: in the past, doctors recommended that people with diverticulitis avoid nuts, seeds, and popcorn. Studies have shown that these foods do not increase the risk of diverticulitis — seeds and some nuts are actually good sources of fiber.
How Diverticulitis Is Diagnosed
A number of conditions can cause pain and other symptoms related to diverticulitis, so your healthcare professional will do an exam and order tests to determine the cause.
During the physical exam, they gently touch different parts of the abdomen to learn where you have pain or tenderness. The exam may also include a pelvic exam to test for disease of the female reproductive organs.
Test | Purpose |
Physical exam | Finds areas of pain and tenderness |
Blood tests | Look for signs of infection and immune-system activity |
Urine test | Rules out other conditions |
Stool test | Rules out other causes |
Pregnancy test | Rules out pregnancy-related causes |
Liver enzyme test | Rules out liver disease |
CT scan | Shows inflamed diverticula, abscesses, fistulas, or other complications |
Treatment Options
Treatment depends on how serious the condition is.
Uncomplicated diverticulitis (mild symptoms, no complications)
If symptoms are mild, you may be treated at home. Your healthcare professional is likely to recommend a liquid diet. When symptoms begin to improve, you gradually increase solid food, beginning with low-fiber foods. When you are fully recovered, you can resume a regular diet with high-fiber foods, and a fiber supplement may also be recommended.
You may also receive a prescription for antibiotics — and you must take all of the pills, even when you are feeling better.
Complicated diverticulitis (serious symptoms or complications)
With serious symptoms or signs of complications, you will likely need to be in the hospital, where antibiotics are given through an intravenous (IV) tube.
Surgery
Relatively simple procedures may drain an abscess or stop bleeding. Surgery on the colon may be needed if you have had complicated diverticulitis, complications such as ruptures in the colon wall or fistulas, multiple episodes of uncomplicated diverticulitis, or a weakened immune system.
Surgery is often performed through small openings in the abdomen (laparoscopic surgery); sometimes a single large opening is needed.
Surgical option | What happens |
Colon reconnection | The diseased section of the colon is removed; the remaining healthy tissues are connected to re-create a complete colon |
Colostomy (temporary) | The healthy and diseased sections are separated; the healthy section is directed to an opening in the abdominal wall, and waste collects in a colostomy bag — giving the diseased section time to heal before the sections are reconnected and the opening is closed |
Other procedures | Treat complications such as peritonitis and fistulas |
Follow-up care
Your healthcare professional may recommend a colonoscopy six weeks or longer after symptoms end. A colonoscopy looks for irregular growths or cancer in the colon or rectum. The recommendation depends on when you last had a colonoscopy and how serious your diverticulitis was.
A note on probiotics
A few small clinical trials found evidence that probiotic supplements — which increase good bacteria in the colon — may reduce the risk of new diverticulitis episodes. However, there is not enough scientific evidence to show that probiotics should be used. Talk to your healthcare professional before taking a probiotic or other supplements.
Preparing for Your Appointment
You may be referred to a gastroenterologist — a doctor who specializes in disorders of the digestive system.
What You Can Do
Ask about pre-appointment restrictions, such as not eating solid food the day before
Write down your symptoms, including any that seem unrelated
List all medicines, vitamins, and supplements with doses and reasons
Note key medical information, including other conditions
Note key personal information, including recent changes or stressors
Ask a relative or friend to come along and help remember what is said
Write down your questions
Questions to Ask
What is the most likely cause of my symptoms?
What tests do I need, and do they require special preparation?
What treatments are available?
How can I prevent diverticulitis from coming back?
Should I remove or add any foods?
How can I manage my other health conditions together?
What Your Doctor May Ask
When did symptoms begin, and how severe are they?
Are they continuous or occasional?
What improves or worsens them?
Have you had a fever?
What medicines and pain relievers do you take?
Any pain with urination?
Have you ever had a colonoscopy (a screening test for colon cancer)?
Frequently Asked Questions
What is diverticulitis?
Diverticulitis is the inflammation or infection of small, bulging pouches (diverticula) that form in the wall of the large intestine. It most often causes sudden, intense pain in the lower left abdomen, along with fever, nausea, and changes in stool habits.
What is the difference between diverticulosis and diverticulitis?
Diverticulosis is simply the presence of pouches in the colon wall — it is not a disease, and most often causes no problems. Diverticulitis happens when one or more of those pouches becomes inflamed or infected.
What does diverticulitis pain feel like?
The pain is most often in the lower left abdomen, and it is usually sudden and intense. It may start mild and gradually worsen, or the intensity may vary over time.
Is diverticulitis serious?
Most cases are mild and improve with rest, diet changes, and antibiotics. But about 15 percent of people develop complications — such as an abscess, colon blockage, fistula, peritonitis, or bleeding — and severe cases need hospital treatment or surgery.
What should you eat with diverticulitis?
During mild symptoms, doctors usually recommend a liquid diet, then gradually add low-fiber solid foods, and finally return to a regular high-fiber diet once fully recovered. Nuts, seeds, and popcorn do not increase the risk and can be part of a healthy high-fiber diet.
Can diverticulitis come back?
Yes — diverticulitis can recur, and multiple episodes may eventually require surgery. Regular exercise, a high-fiber diet with plenty of fluids, a healthy weight, quitting smoking, and limiting alcohol all help lower the risk of new episodes.
When is surgery needed for diverticulitis?
Colon surgery may be needed after complicated diverticulitis, serious tissue damage such as ruptures or fistulas, multiple episodes of uncomplicated diverticulitis, or in people with weakened immune systems. A follow-up colonoscopy is often recommended six or more weeks after symptoms resolve.
Conclusion
Diverticulitis starts with ordinary pouches — diverticula are common after 50 and usually harmless (diverticulosis), but when a pouch inflames or gets infected, it causes intense lower-left belly pain, fever, and stool changes.
Mild cases heal with rest, diet, and antibiotics — while severe or complicated cases need the hospital, IV antibiotics, and sometimes surgery to repair or remove diseased colon sections.
Prevention is very much in your hands — high-fiber foods, fluids, regular vigorous exercise, a healthy weight, and no smoking significantly lower your risk, and old fears about nuts, seeds, and popcorn are outdated.
This guide walked through what diverticulitis is, the warning signs, the risk factors, how it is diagnosed and treated, and how to keep it from coming back. If you're exploring more digestive health topics, our complete guides to diarrhea and traveler's diarrhea go deeper, and you can explore more at rinnit.com.
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This content is provided for general educational purposes only and is not a substitute for professional medical advice. Always consult a qualified healthcare professional for diagnosis and treatment.
Related Reading
When diverticulitis needs an operation: Diverticulitis Surgery: Types, Procedure, Recovery and Risks
Ileostomy: Types, Surgery, Recovery, Stoma Care and Reversal explains when an ileostomy is needed, the loop and end types, what happens during surgery, recovery and reversal.
Barium Enema (Lower GI Series): Purpose, Preparation, Procedure and Results explains the colon X-ray test that can help find this condition.
Colonoscopy: Purpose, Prep, Procedure, Results and Risks: A colonoscopy can show the small pouches of diverticulosis and help rule out other causes of bowel symptoms.
Learn more in our guide to CT Scan: What It Shows, How It Works, Risks and Results.
Learn more in our guide to Flexible Sigmoidoscopy: Prep, Procedure, Results and Risks.
Fecal Occult Blood Test (FOBT): Types, Preparation, Results and Next Steps explains the stool test that checks for hidden bleeding linked to this condition.
References
Mayo Clinic Staff. Diverticulitis - Symptoms and causes. Mayo Clinic. October 22, 2024. https://www.mayoclinic.org/diseases-conditions/diverticulitis/symptoms-causes/syc-20371758
Mayo Clinic Staff. Diverticulitis - Diagnosis and treatment. Mayo Clinic. October 22, 2024. https://www.mayoclinic.org/diseases-conditions/diverticulitis/diagnosis-treatment/drc-20371764
Strate LL, et al. Nut, corn, and popcorn consumption and the incidence of diverticular disease. JAMA. 2008;300(8):907-14. PMID 18728264. https://doi.org/10.1001/jama.300.8.907
Ma W, et al. Lifestyle factors, genetic susceptibility and risk of incident diverticulitis: an integrated analysis of four prospective cohort studies and electronic health records-linked biobank. Gut. 2025;74(12):2004-2011. PMID 40592564. https://doi.org/10.1136/gutjnl-2025-335364
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