Diverticulitis Symptoms and Treatment: What to Know

What is the difference between diverticulosis and diverticulitis?

Diverticulosis is the presence of diverticula — small outpouchings that develop in the colon wall, typically in the sigmoid colon. It is very common, affecting more than 30% of U.S. adults between ages 50 and 59, and usually causes no symptoms. Most people with diverticulosis never develop diverticulitis 2Ref 2National Institute of Diabetes and Digestive and Kidney Diseases (2021).Diverticular Disease.Prevalence of diverticulosis (>30% of adults 50-59), distinction from diverticulitis, recurrence rates, and post-episode lifestyle guidance.

Diverticulitis occurs when one or more of those pouches becomes inflamed. This can range from a localized micro-perforation that the body walls off (uncomplicated diverticulitis) to frank perforation with abscess formation or diffuse peritonitis (complicated diverticulitis) 1Ref 1Qaseem A, Etxeandia-Ikobaltzeta I, Lin JS, Fitterman N, Shamliyan T, Wilt TJ (2022).Diagnosis and Management of Acute Left-Sided Colonic Diverticulitis: A Clinical Guideline From the American College of Physicians.Symptoms, CT diagnosis, treatment algorithm including selective antibiotic use and hospitalization criteria; post-episode colonoscopy recommendation.

So diverticulosis is the underlying anatomical condition; diverticulitis is the acute complication. Having diverticulosis does not mean a diverticulitis episode is inevitable.

What are the symptoms of diverticulitis?

The hallmark symptom is abdominal pain — typically in the left lower quadrant, though right-sided involvement occurs and is more common in younger patients and in Asian populations 1Ref 1Qaseem A, Etxeandia-Ikobaltzeta I, Lin JS, Fitterman N, Shamliyan T, Wilt TJ (2022).Diagnosis and Management of Acute Left-Sided Colonic Diverticulitis: A Clinical Guideline From the American College of Physicians.Symptoms, CT diagnosis, treatment algorithm including selective antibiotic use and hospitalization criteria; post-episode colonoscopy recommendation. Other common symptoms include:

• Fever and chills — indicating inflammatory or infectious involvement
• Nausea and sometimes vomiting
• Change in bowel habits — constipation, diarrhea, or alternating between the two
• Tenderness when pressing on the lower abdomen
• Bloating

Some people also notice blood in the stool, though significant rectal bleeding is more characteristic of diverticular bleeding (a separate complication of diverticulosis, distinct from diverticulitis).

Symptoms can develop over one to two days and may initially resemble constipation or gas pain. If pain persists or worsens, especially with fever, see a clinician promptly.

How is diverticulitis diagnosed?

Clinical assessment begins with symptoms, physical examination (tenderness and whether the abdomen is soft or rigid), and vital signs.

CT scan of the abdomen and pelvis is the standard imaging test — it confirms diverticulitis, rules out other causes of abdominal pain (appendicitis, ovarian pathology, bowel obstruction), and classifies the episode as uncomplicated or complicated (abscess, perforation, fistula) 1Ref 1Qaseem A, Etxeandia-Ikobaltzeta I, Lin JS, Fitterman N, Shamliyan T, Wilt TJ (2022).Diagnosis and Management of Acute Left-Sided Colonic Diverticulitis: A Clinical Guideline From the American College of Physicians.Symptoms, CT diagnosis, treatment algorithm including selective antibiotic use and hospitalization criteria; post-episode colonoscopy recommendation.

Blood tests typically include a complete blood count (looking for elevated white blood cells) and C-reactive protein (CRP). These support the diagnosis but are not specific.

Colonoscopy is not performed during an acute episode but is often recommended 6 to 8 weeks after resolution to evaluate the colon and ensure no alternative diagnosis (such as colorectal cancer) was missed 1Ref 1Qaseem A, Etxeandia-Ikobaltzeta I, Lin JS, Fitterman N, Shamliyan T, Wilt TJ (2022).Diagnosis and Management of Acute Left-Sided Colonic Diverticulitis: A Clinical Guideline From the American College of Physicians.Symptoms, CT diagnosis, treatment algorithm including selective antibiotic use and hospitalization criteria; post-episode colonoscopy recommendation2Ref 2National Institute of Diabetes and Digestive and Kidney Diseases (2021).Diverticular Disease.Prevalence of diverticulosis (>30% of adults 50-59), distinction from diverticulitis, recurrence rates, and post-episode lifestyle guidance.

How is diverticulitis treated?

Treatment depends on whether the episode is uncomplicated or complicated 1Ref 1Qaseem A, Etxeandia-Ikobaltzeta I, Lin JS, Fitterman N, Shamliyan T, Wilt TJ (2022).Diagnosis and Management of Acute Left-Sided Colonic Diverticulitis: A Clinical Guideline From the American College of Physicians.Symptoms, CT diagnosis, treatment algorithm including selective antibiotic use and hospitalization criteria; post-episode colonoscopy recommendation:

Uncomplicated diverticulitis (mild, no abscess or perforation) Many patients can be managed at home with: - A temporary liquid or low-fiber diet to rest the bowel - Acetaminophen for pain (NSAIDs are typically avoided) - Antibiotics — increasingly used selectively rather than routinely in otherwise healthy patients with mild episodes, based on clinical trial evidence - Close monitoring: return to the clinician or emergency room if symptoms worsen

Complicated diverticulitis - Pericolic abscess: small abscesses may resolve with IV antibiotics; larger ones require CT-guided drainage - Perforation with peritonitis: surgical emergency - Fistula: abnormal connection from the colon to the bladder, skin, or other structures — typically requires planned surgery - Obstruction: managed with surgery when severe

Hospitalization is needed when: - Oral fluids cannot be tolerated - Fever is high, pain is severe, or labs show significant infection markers - CT shows complicated disease - The patient is immunocompromised 1Ref 1Qaseem A, Etxeandia-Ikobaltzeta I, Lin JS, Fitterman N, Shamliyan T, Wilt TJ (2022).Diagnosis and Management of Acute Left-Sided Colonic Diverticulitis: A Clinical Guideline From the American College of Physicians.Symptoms, CT diagnosis, treatment algorithm including selective antibiotic use and hospitalization criteria; post-episode colonoscopy recommendation3Ref 3National Institute of Diabetes and Digestive and Kidney Diseases (2021).Treatment for Diverticular Disease.Treatment options for uncomplicated and complicated diverticulitis including hospitalization criteria and when surgery is appropriate

What happens after a diverticulitis episode?

After recovery, your clinician will usually:

• Recommend a follow-up colonoscopy in 6 to 8 weeks
• Advise a gradual return to a high-fiber diet once fully recovered
• Discuss recurrence risk — after a first uncomplicated episode managed non-surgically, the risk of a second episode exists but many people never experience recurrence 2Ref 2National Institute of Diabetes and Digestive and Kidney Diseases (2021).Diverticular Disease.Prevalence of diverticulosis (>30% of adults 50-59), distinction from diverticulitis, recurrence rates, and post-episode lifestyle guidance
• Counsel on lifestyle factors: maintaining a healthy weight, regular exercise, adequate hydration, and avoiding regular NSAID use

For people with recurrent episodes or complicated disease, referral to a colorectal surgeon to discuss elective surgery may be appropriate 1Ref 1Qaseem A, Etxeandia-Ikobaltzeta I, Lin JS, Fitterman N, Shamliyan T, Wilt TJ (2022).Diagnosis and Management of Acute Left-Sided Colonic Diverticulitis: A Clinical Guideline From the American College of Physicians.Symptoms, CT diagnosis, treatment algorithm including selective antibiotic use and hospitalization criteria; post-episode colonoscopy recommendation. A Gale primary care clinician can coordinate this evaluation and manage your ongoing follow-up.