Diverticulitis Explained: Causes, Symptoms & Care

Diverticulitis is essentially an inflammation of already existing small pouches (called diverticula) in the intestinal lining. It’s a relatively common disorder of the gastrointestinal tract seen in clinical practice.While it was once considered an almost inevitable complication in older adults with diverticulosis, research now shows that diverticulitis can also affect younger people. Factors such as diet, lifestyle habits,obesity, smoking, and certain medical conditions contribute to this shift.

In some people, the disease remains mild and can be treated with simple conservative measures; for others, it can quickly develop into an abscess, perforation, or fistula. These require hospitalization or surgery. Recurrence is another concern, but can be prevented with proper treatment and lifestyle changes.

What is Diverticulitis?

Diverticulitis refers to inflammation or infection of small, bulging, balloon-like pouches (diverticula) that can form in the lining of the colon.^[1] Most people with these pouches, a condition called diverticulosis, never know they have them. Diverticulitis represents the point at which these pouches become clinically significant.

Diverticulosis vs Diverticulitis:

Diverticulosis and diverticulitis are related but distinct conditions. While diverticulosis refers to the mere presence of diverticula in the colon, diverticulitis develops when these pouches become inflamed or infected.^[2]

Comparison of Diverticulosis vs Diverticulitis: Factors like Pathophysiology, Clinical Presentation, and Treatment.

Epidemiology

It is actually a very common disease, especially in developed countries. It is more frequent in people over the age of 40 years, but younger adults can also have diverticulitis. The lifetime risk of diverticulitis in a person with diverticulosis was reported to range from 10% to 25%.^[3] Also, there are some unique geographical stats; countries from the West have more of left-sided diverticulitis but the countries from the East and Asia suffer from more right-sided diverticulitis.

There are many risk factors which can increase the chances of developing diverticulitis. Here are some of them: lifestyle choices make a big impact; low fiber diet, no exercise, and abdominal obesity has its price to pay when it comes to diverticulitis. There are some sex-related incidence patterns also: men younger than 50 years of age and women above 50 years of age tend to be more affected by this disease.^[4]

Diverticulitis Causes & Risk Factors

The exact cause isn’t fully understood, but several factors contribute to the development process of diverticulitis:

• Fecalith (hard bits of stool) cause obstruction of a diverticulum → increased intraluminal pressure → micro-tears
• Changes in colonic microbiome and local infection
• Chronic inflammation of the colonic wall

Inflammation starts when fecaliths or small particles of undigested food gets trapped in the diverticulum (pocket) which in turn raises the pressure inside it causing micro-tears/perforations in the wall.

Bacterial growth leads to inflammation, which, in uncomplicated cases, remains confined to the bowel wall and pericolic fat. In severe cases, infection can advance to an abscess, perforation, fistula formation, even peritonitis.^[5]

Schematic representation of the pathophysiological mechanisms underlying SUDD (symptomatic uncomplicated diverticular disease). (Image Courtesy: Barbaro, M. R., Cremon, C., Fuschi, D., Marasco, G., Palombo, M., Stanghellini, V., & Barbara, G. (2021). Pathophysiology of Diverticular Disease: From Diverticula Formation to Symptom Generation. International Journal of Molecular Sciences, 23(12), 6698. Available fromMDPI. Licenced under CC by 4.0)

Preventable Risk Factors:

• Low-fiber diet with processed foods
• Lack of exercise and sedentary lifestyle
• Obesity especially fat in the abdominal region
• Smoking, because it damages vessels and slows healing
• Excessive use of NSAIDs (ibuprofen, naproxen) and corticosteroids
• Excessive red meat consumption

Non-Preventable Risk Factors:

• Age over 40^[6]
• Genetics and family history
• Previous history of diverticulitis

Symptoms & Clinical Presentation of Diverticulitis

Clinical presentation shows some patterns that help identify the condition.

• Abdominal pain which is localized to the left lower quadrant in Western patients, can be right-sided in Asian populations.^[7] Easy to differentiate it from typical gas or indigestion because it doesn’t come and go in waves but stays constant and even worsens over hours.
• Fever and chills are systemic signs of infection. A low-grade fever (100-101°F), along with chills, fatigue, and a general feeling of being unwell.
• Altered bowel habits out of which constipation is more common than diarrhea, though either can occur.
• Nausea and vomiting secondary to ileus or partial obstruction.

In the case complications develop, distinct features can be seen:

• Urinary symptoms (frequency, urgency, dysuria) if inflammation irritates the bladder
• Rectal bleeding (less common but possible)
• Fistula formation (e.g., colovesicalfistula)^[8] can present with pneumaturia or fecaluria.
• Rigid abdomen if perforation and peritonitis develop

Symptoms that necessitate immediate medical attention:

• Severe abdominal pain
• High fever over 101°F
• Signs of sepsis
• Rigid abdomen
• Persistent vomiting
• Dehydration signs
• Blood in stool
• Severe constipation with no gas

Diagnosis of Diverticulitis

Diagnosis is clinical with some labs and imaging needed. Aim is to show that there is inflammation in the diverticulum and to see if it is complicated or not.

Healthcare providers will:

1. Review your symptoms and medical history
2. Perform a physical exam, checking for:
3. Advise laboratory tests to check for^[9]:
4. Get imaging studies done to confirm the diagnosis:

CT scan with IV Contrast demonstrating wall thickening of the left colon with perivisceritis (asterisk) and localized extraluminal air adjacent to the inflamed segment (arrow). (Image Courtesy: Tiralongo, F., Di Pietro, S., Milazzo, D., Galioto, S., Castiglione, D. G., Foti, P. V., Mosconi, C., Giurazza, F., Venturini, M., Nicola, G., Palmucci, S., & Basile, A. (2022). Acute Colonic Diverticulitis: CT Findings, Classifications, and a Proposal of a Structured Reporting Template. Diagnostics, 13(24), 3628. Available fromMDPI. Licenced under CC by 4.0)

Recommended Clinical Approach:

Patients with mild, localized symptoms and no systemic toxicity may be diagnosed clinically in resource-limited settings, but confirmatory imaging is strongly preferred in modern practice.

Hinchey Classification of Diverticulitis

Class	CT Findings12Hawkins, A. T., Wise, P. E., Chan, T., Lee, J. T., Mullaney, T. G., Wood, V., Eglinton, T., Frizelle, F., Khan, A., Hall, J., Ilyas, M. M., Michailidou, M., Nfonsam, V. N., Cowan, M., Williams, J., Steele, S. R., Alavi, K., Ellis, C. T., Collins, D., . . . Lightner, A. L. (2020). Diverticulitis – An Update from the Age Old Paradigm. Current Problems in Surgery, 57(10), 100862. https://doi.org/10.1016/j.cpsurg.2020.100862
Stage 0	Mild clinical diverticulitis
Stage Ia	Confined pericolic inflammation/phlegmon
Stage Ib	Confined pericolic abscess (within sigmoid mesocolon)
Stage II	Pelvic, distant intra-abdominal or intraperitoneal abscess
Stage III	Generalized purulent peritonitis
Stage IV	Fecal peritonitis

Differential Diagnosis of Diverticulitis

Condition	Key Clinical Features	Imaging / Diagnostic Clues	Distinguishing Factors vs. Diverticulitis
Colon Cancer	Gradual onset, altered bowel habits, weight loss, anemia	CT may show an irregular mass, apple-core lesion onbarium enema13Alzaraa, A., Krzysztof, K., Uwechue, R. et al. Apple-core lesion of the colon: a case report. Cases Journal 2, 7275 (2009). https://doi.org/10.4076/1757-1626-2-7275, colonoscopy confirms	Symptoms progress more insidiously; obstructive features common
Appendicitis	RLQ pain, anorexia, nausea/vomiting, fever	CT/US: inflamed appendix, periappendiceal fat stranding	Pain location (RLQ vs. LLQ); younger patients more common
Inflammatory Bowel Disease (Crohn’s, UC)	Chronic diarrhea, abdominal pain, rectal bleeding, systemic symptoms	Colonoscopy with biopsy diagnostic	More diffuse colonic involvement, chronic course, extraintestinal manifestations
Ischemic Colitis	Sudden crampy pain (often left-sided), bloody diarrhea, in elderly/vascular risk	CT: segmental colonic wall thickening, thumbprinting; colonoscopy shows pale mucosa with ulcerations	Bloody diarrhea is more prominent; linked to vascular compromise
Irritable Bowel Syndrome (IBS)	Chronic abdominal discomfort, bloating, altered bowel habits, no systemic signs	Normal labs, imaging, colonoscopy	No fever, leukocytosis, or imaging evidence of inflammation
Gynecologic Pathologies (e.g., ovarian cyst, ectopic pregnancy, PID)	Pelvic pain, menstrual irregularities, vaginal discharge or bleeding	Pelvic US key	Gynecologic history, adnexal tenderness, positive pregnancy test
Urinary Tract Infection / Pyelonephritis	Dysuria, frequency, flank pain, fever	UA: pyuria, bacteriuria; CT/US: renal changes	Urinary symptoms predominate; lacks pericolic fat stranding
Epiploic Appendagitis	Acute localized LLQ pain, mild systemic symptoms	CT: fat-density lesion adjacent to colon with hyperattenuating rim	Benign, self-limited; no bowel wall thickening as in diverticulitis

Treatment & Management of Diverticulitis

Mild, Uncomplicated Diverticulitis:

Outpatient management is opted for in stable patients with mild disease, good oral intake, and reliable follow-up.

Rest & Diet Modification

• Clear liquids initially: broth, gelatin, clear juices
• Slowly introduce low-fiber foods as symptoms improve
• Avoid nuts, seeds, and high-fiber food in active inflammation

Pain Management

• Acetaminophen (Tylenol) for pain
• Avoid NSAIDs (ibuprofen, naproxen)

Antibiotics

• Historically prescribed for all, but recent guidelines (e.g., American Gastroenterological Association, 2021) suggest antibiotics may be omitted in otherwise healthy patients with mild, uncomplicated disease.^[10]
• When prescribed, options include: Ciprofloxacin + metronidazole, Amoxicillin-clavulanate

Moderate-Severe Diverticulitis:

Hospital treatment may include:

• IV antibiotics (broader spectrum, 7-10 day course)
• Bowel rest with IV fluids to prevent dehydration
• Gradual reintroduction of food
• Stronger pain medications
• Close monitoring for complications

Complicated Diverticulitis:

Defined by abscess, perforation, fistula, obstruction, or peritonitis.

• Abscess (Hinchey I–II):
• Peritonitis or free perforation (Hinchey III–IV):
• Fistula or obstruction: Elective surgical resection is usually indicated after acute inflammation subsides.

Dietary Guidelines in Diverticulitis

Diet plays a crucial role in both managing acute diverticulitis and preventing future episodes.

During Acute Inflammation:

The digestive system needs rest during flare-ups. Start with clear liquids (water, clear broths, gelatin, clear fruit juices) that provide hydration with minimal digestive burden. As symptoms improve, gradually advance to low-fiber foods like white rice, pasta, cooked vegetables without skins, eggs, fish, and tender meats.

There are some foods that should be temporarily avoided during the flare-ups:

• Nuts, seeds, and popcorn (though recent studies suggest the risk is lower than previously assumed)
• Raw vegetables and fruits with skins
• Whole grains and high-fiber cereals
• Beans and legumes
• Spicy or fried foods

Recovery & Long-Term Diet:

In the recovery phase, the dietary strategy completely reverses. Instead of avoiding fiber, a gradual transition to a high-fiber diet is recommended to prevent future flares.

The goal is 25-35 grams of fiber daily15Hawkins, A. T., Wise, P. E., Chan, T., Lee, J. T., Mullaney, T. G., Wood, V., Eglinton, T., Frizelle, F., Khan, A., Hall, J., Ilyas, M. M., Michailidou, M., Nfonsam, V. N., Cowan, M., Williams, J., Steele, S. R., Alavi, K., Ellis, C. T., Collins, D., . . . Lightner, A. L. (2020). Diverticulitis – An Update from the Age Old Paradigm. Current Problems in Surgery, 57(10), 100862. https://doi.org/10.1016/j.cpsurg.2020.100862, but this should be achieved slowly: adding about 5 grams per week to avoid gas and bloating. Adequate water intake becomes crucial during this phase, as fiber needs fluid to work effectively. Aim for at least 8 glasses of water daily.

The best sources of high-fiber foods include:

• Fruits (pears, apples, berries, oranges)
• Vegetables (leafy greens, carrots, spinach, zucchini)
• Whole grains (brown rice, oats, whole wheat bread)
• Legumes (lentils, beans, chickpeas, though these should be introduced gradually)

Incorporating anti-inflammatory foods into your diet may provide additional benefits. These include fatty fish rich in omega-3 fatty acids (salmon, mackerel, sardines), olive oil, leafy greens, berries, and yogurt with beneficial probiotics.

Myths & Facts about Diverticulitis:

Myth: Nuts and seeds will get stuck and cause flares

For a long time, doctors recommended avoiding nuts/seeds/popcorn, because they thought tiny bits could become lodged in diverticula. Many large studies have refuted this immediately – these foods don’t cause diverticulitis or complications.^[11] (If you do have diverticula, your intestines are covered in little pockets, so tiny bits of food are naturally “stuck” to them all day.)

Myth: Once you have diverticulitis, it will continue to escalate over time

If you have ever had one episode of diverticulitis, it’s common to feel like a death sentence. “What if it was worse next time? And worse after that? What if I have bad complications?” In reality, the vast majority of people who follow prevention strategies (high fiber diet, exercise, avoid smoking) never have a serious complications and often never have frequent recurrences.

Do Probiotics Help?

Probiotics certainly have their role in treating diverticulitis and preventing recurrences, and research shows positive initial signs. The probiotics can restore balance in the microbiome and reduce inflammation.

However, the best probiotic for diverticulitis is a multi-strain product that contains Lactobacillus plantarum, Lactobacillus acidophilus, and Bifidobacterium strains. These are the strains that have been most studied. Also important to consider: probiotics should not replace proven treatments such as dietary changes and lifestyle considerations.

Lifestyle Changes for Prevention

Prevention of diverticulitis recurrence relies heavily on lifestyle modifications that address modifiable risk factors. These changes not only reduce the chances of future episodes but also contribute to overall digestive and general health.

Exercise & Weight Management:

• Regular physical activity significantly reduces diverticulitis risk. Aim for 150 minutes of moderate cardio weekly, along with strength training twice per week. Exercise improves bowel function, reduces inflammation, and helps maintain healthy weight.
• Weight management is crucial since obesity, particularly abdominal fat, increases inflammation and disease risk. If weight loss is needed, aim for 1-2 pounds per week through diet and exercise.

Smoking Cessation:

• Smoking impairs blood flow to the digestive tract, increases infection risk, and delays healing. It also significantly increases the likelihood of serious complications.
• Consider nicotine replacement therapy, medications, counseling, or support programs to quit.

Stress Management:

• Chronic stress affects digestion and immune function, potentially contributing to flare-ups. Effective stress management includes regular exercise, adequate sleep (7-9 hours), meditation or relaxation techniques, and maintaining social connections.

Medication Considerations:

• NSAIDs and corticosteroids’ unprescribed use should be avoided as they increase the risk of perforation and recurrence.
• Prophylactic agents such as rifaximin or mesalamine have an uncertain role, with mixed evidence and no current guideline endorsement for routine use.^[12]

Prevention can be best achieved by combining a high-fiber diet, hydration, exercise, and avoidance of modifiable risk factors, rather than pharmacological interventions.

Complications & Recurrence

Diverticulitis ranges from mild inflammation to life-threatening complications:

• Abscess formation: Infected fluid pockets causing fever and pain. Small ones may respond to antibiotics; large ones need drainage.
• Perforation: Free perforation with peritonitis is a surgical emergency. Patients have diffuse pain, guarding, and systemic illness.
• Fistulae: Chronic inflammation creates abnormal connections between colon and other organs, commonly to bladder causing urinary symptoms.
• Obstruction: Scar tissue narrows the intestine, causing cramping, vomiting, and inability to pass gas. May require surgery.
• Bleeding: Less common but possible during active inflammation.

Recurrence:

After initial uncomplicated diverticulitis, 10-30% have recurrence over several years. Most recurrent episodes are similar or milder than the first. Young age at onset, obesity, smoking, and low-fiber diet increase recurrence risk.

Conclusion

Diverticulitis is a common, generally manageable condition ranging from mild inflammation to serious complications requiring surgery. Success depends on early recognition, appropriate treatment, and long-term prevention strategies.

Most people recover completely and prevent future episodes through lifestyle changes; maintaining high-fiber diet, staying active, and avoiding risk factors like smoking and excessive NSAID use. While concerning initially, most patients live normal, healthy lives with minimal impact from their diagnosis.

References

[1] InformedHealth.org [Internet]. Cologne, Germany: Institute for Quality and Efficiency in Health Care (IQWiG); 2006-. Overview: Diverticular disease and diverticulitis. [Updated 2021 Dec 28]. Available from: https://www.ncbi.nlm.nih.gov/books/NBK507004/

[2] Bhatia, M., & Mattoo, A. (2023). Diverticulosis and Diverticulitis: Epidemiology, Pathophysiology, and Current Treatment Trends. Cureus, 15(8), e43158. https://doi.org/10.7759/cureus.43158

[3] Strate, L. L., & Morris, A. M. (2019). Epidemiology, Pathophysiology, and Treatment of Diverticulitis. Gastroenterology, 156(5), 1282. https://doi.org/10.1053/j.gastro.2018.12.033

[4] Bharucha, A. E., Parthasarathy, G., Ditah, I., Fletcher, J. G., Ewelukwa, O., Pendlimari, R., Yawn, B. P., Schleck, C., & Zinsmeister, A. R. (2015). Temporal Trends in the Incidence and Natural History of Diverticulitis: A Population-Based Study. The American Journal of Gastroenterology, 110(11), 1589. https://doi.org/10.1038/ajg.2015.302

[5] Strate, L. L., & Morris, A. M. (2019). Epidemiology, Pathophysiology, and Treatment of Diverticulitis. Gastroenterology, 156(5), 1282. https://doi.org/10.1053/j.gastro.2018.12.033

[6] Hawkins, A. T., Wise, P. E., Chan, T., Lee, J. T., Mullaney, T. G., Wood, V., Eglinton, T., Frizelle, F., Khan, A., Hall, J., Ilyas, M. M., Michailidou, M., Nfonsam, V. N., Cowan, M., Williams, J., Steele, S. R., Alavi, K., Ellis, C. T., Collins, D., . . . Lightner, A. L. (2020). Diverticulitis – An Update from the Age Old Paradigm. Current Problems in Surgery, 57(10), 100862. https://doi.org/10.1016/j.cpsurg.2020.100862

[7] Imaeda, H., & Hibi, T. (2018). The Burden of Diverticular Disease and Its Complications: West versus East. Inflammatory intestinal diseases, 3(2), 61–68. https://doi.org/10.1159/000492178

[8] Carr S, Velasco AL. Colon Diverticulitis. [Updated 2024 Jul 25]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2025 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK541110/

[9] Hawkins, A. T., Wise, P. E., Chan, T., Lee, J. T., Mullaney, T. G., Wood, V., Eglinton, T., Frizelle, F., Khan, A., Hall, J., Ilyas, M. M., Michailidou, M., Nfonsam, V. N., Cowan, M., Williams, J., Steele, S. R., Alavi, K., Ellis, C. T., Collins, D., . . . Lightner, A. L. (2020). Diverticulitis – An Update from the Age Old Paradigm. Current Problems in Surgery, 57(10), 100862. https://doi.org/10.1016/j.cpsurg.2020.100862

[10] Andeweg, C. S., Wegdam, J. A., Groenewoud, J., van der Wilt, G. J., van Goor, H., & Bleichrodt, R. P. (2014). Toward an evidence-based step-up approach in diagnosing diverticulitis. Scandinavian Journal of Gastroenterology, 49(7), 775–784. https://doi.org/10.3109/00365521.2014.908475

[11] Stollman, N., Smalley, W., Hirano, I., & AGA Institute Clinical Guidelines Committee (2015). American Gastroenterological Association Institute Guideline on the Management of Acute Diverticulitis. Gastroenterology, 149(7), 1944–1949. https://doi.org/10.1053/j.gastro.2015.10.003

[12] Hawkins, A. T., Wise, P. E., Chan, T., Lee, J. T., Mullaney, T. G., Wood, V., Eglinton, T., Frizelle, F., Khan, A., Hall, J., Ilyas, M. M., Michailidou, M., Nfonsam, V. N., Cowan, M., Williams, J., Steele, S. R., Alavi, K., Ellis, C. T., Collins, D., . . . Lightner, A. L. (2020). Diverticulitis – An Update from the Age Old Paradigm. Current Problems in Surgery, 57(10), 100862. https://doi.org/10.1016/j.cpsurg.2020.100862

[13] Alzaraa, A., Krzysztof, K., Uwechue, R. et al. Apple-core lesion of the colon: a case report. Cases Journal 2, 7275 (2009). https://doi.org/10.4076/1757-1626-2-7275

[14] Peery, A. F., Shaukat, A., & Strate, L. L. (2021). AGA Clinical Practice Update on Medical Management of Colonic Diverticulitis: Expert Review. Gastroenterology, 160(3), 906-911.e1. https://doi.org/10.1053/j.gastro.2020.09.059

[15] Hawkins, A. T., Wise, P. E., Chan, T., Lee, J. T., Mullaney, T. G., Wood, V., Eglinton, T., Frizelle, F., Khan, A., Hall, J., Ilyas, M. M., Michailidou, M., Nfonsam, V. N., Cowan, M., Williams, J., Steele, S. R., Alavi, K., Ellis, C. T., Collins, D., . . . Lightner, A. L. (2020). Diverticulitis – An Update from the Age Old Paradigm. Current Problems in Surgery, 57(10), 100862. https://doi.org/10.1016/j.cpsurg.2020.100862

[16] Hawkins, A. T., Wise, P. E., Chan, T., Lee, J. T., Mullaney, T. G., Wood, V., Eglinton, T., Frizelle, F., Khan, A., Hall, J., Ilyas, M. M., Michailidou, M., Nfonsam, V. N., Cowan, M., Williams, J., Steele, S. R., Alavi, K., Ellis, C. T., Collins, D., . . . Lightner, A. L. (2020). Diverticulitis – An Update from the Age Old Paradigm. Current Problems in Surgery, 57(10), 100862. https://doi.org/10.1016/j.cpsurg.2020.100862

[17] Hawkins, A. T., Wise, P. E., Chan, T., Lee, J. T., Mullaney, T. G., Wood, V., Eglinton, T., Frizelle, F., Khan, A., Hall, J., Ilyas, M. M., Michailidou, M., Nfonsam, V. N., Cowan, M., Williams, J., Steele, S. R., Alavi, K., Ellis, C. T., Collins, D., . . . Lightner, A. L. (2020). Diverticulitis – An Update from the Age Old Paradigm. Current Problems in Surgery, 57(10), 100862. https://doi.org/10.1016/j.cpsurg.2020.100862