Overview
Diverticulitis occurs when small pouches (diverticula) that can form in the wall of the colon become inflamed or infected. Most people with diverticula have no symptoms (diverticulosis), but in some the pouches become inflamed, causing pain, fever, and bowel changes.
How common is it?
Diverticulosis becomes more common with age, but most people with these pouches do not develop diverticulitis. NIDDK reports that fewer than 5% of people with diverticulosis develop diverticulitis.
Causes and risk factors
Increased pressure inside the colon, often from a low-fibre diet leading to hard stools and straining, is thought to cause the bowel wall to bulge outward. Diverticulitis occurs when these pouches become blocked and inflamed.
Common risk factors
- Low dietary fibre intake
- Age over 40
- Obesity
- Physical inactivity
- Red meat consumption
- Smoking
- Use of NSAIDs and steroids
- Constipation
Symptoms
- Sudden, often severe pain in the lower left abdomen
- Fever and chills
- Nausea and vomiting
- Change in bowel habit (constipation or diarrhoea)
- Tenderness over the affected area
- Blood in stools (uncommon in uncomplicated cases)
When to see a doctor
Seek urgent medical assessment for new significant or worsening abdominal pain, particularly with fever or vomiting. Severe pain with a rigid or swollen abdomen, inability to pass stool or wind, heavy rectal bleeding, collapse or confusion needs emergency assessment. Do not wait for every symptom or for fever to appear.
Diagnosis
CT scan with contrast is the preferred investigation. It confirms diagnosis, grades severity, and identifies complications such as abscess or perforation. Blood tests show infection markers.
Treatments
Assessment and supportive care for uncomplicated cases
A clinician may manage uncomplicated diverticulitis at home. Antibiotics may not be needed if you are otherwise well; they are more likely to be needed if you are systemically unwell, immunosuppressed or have significant other illness. Follow individual advice on pain relief, fluids and diet, and seek reassessment if symptoms persist or worsen.
Hospital treatment for severe cases
Intravenous antibiotics, fluids, and bowel rest. CT-guided drainage for abscesses. Pain relief.
Surgery
Colectomy (removal of the affected bowel section) for perforation, repeated severe attacks, fistula, or bowel obstruction.
Self-care and lifestyle
- Increase dietary fibre gradually after recovery to prevent recurrence
- Maintain adequate hydration
- Exercise regularly to maintain bowel transit
- Avoid prolonged constipation
Prevention
High-fibre diet, plenty of water, regular exercise, and maintaining healthy weight reduce the risk of diverticulosis developing and of diverticulitis episodes.
Sources for targeted updates
Updated: 24 October 2026. Targeted corrections to frequency, treatment, urgent-care guidance. This update covers the named sections; a full review of the remaining guide is pending.