What is diverticulitis?

Diverticulitis is inflammation or infection of diverticula — small pouches that form in the colon wall, common over age 40. Symptoms include constant lower left abdominal pain, fever, and change in bowel habit. Mild cases treated with antibiotics at home; severe cases need hospital admission. High-fibre diet helps prevent diverticular disease. Seek urgent help for severe pain, vomiting, or inability to pass wind — possible perforation or abscess.

What are the symptoms of diverticulitis?

Constant abdominal pain — usually left lower quadrant, fever, nausea, constipation or diarrhoea, bloating, blood in stool sometimes. Pain worsens with movement. Unlike diverticulosis which is silent, diverticulitis is painful and systemic illness.

What causes diverticular disease?

Low-fibre Western diet increases colon pressure causing pouches (diverticulosis) in weak spots of colon wall. Faecal matter trapping in pouches can cause inflammation and bacterial infection (diverticulitis). Age, obesity, smoking, and inactivity increase risk.

How is diverticulitis treated?

Uncomplicated — oral antibiotics (co-amoxiclav or ciprofloxacin + metronidazole), paracetamol not NSAIDs initially, clear fluids progressing to low fibre then high fibre after recovery. Complicated — hospital IV antibiotics, CT scan, abscess drainage, surgery if perforated or recurrent severe episodes.

Should I avoid nuts and seeds with diverticular disease?

No — old advice disproven. Nuts, seeds, and popcorn do not cause diverticulitis. When recovered, high-fibre diet reduces recurrence risk. During acute attack, temporary low-fibre diet as advised.

Does diverticulitis lead to colon cancer?

Diverticular disease does not cause cancer but symptoms overlap — colonoscopy recommended after first episode in age-appropriate patients or if alarm features — to exclude malignancy. Repeated episodes may lower threshold for colonoscopy.

Diverticulitis: Symptoms, Causes & Treatment

Diverticulitis — when colon pouches flare

Diverticulosis — presence of diverticula (outpouchings of colon mucosa through muscle wall) — very common — 50% over 60 on colonoscopy.

Diverticulitis — inflammation ± infection of diverticula — painful, febrile illness — 5% with diverticulosis experience this.

Diverticulosis vs diverticulitis

	Diverticulosis	Diverticulitis
Symptoms	Usually none	Pain, fever, malaise
Treatment	High fibre prevention	Antibiotics, sometimes surgery
Bleeding	Painless PR bleed possible	Less common

Symptoms of diverticulitis

Uncomplicated:

constant LLQ pain — left lower abdomen ( sigmoid colon — Western pattern; right-sided in Asia)
fever
change bowel habit — constipation or diarrhoea
nausea
tenderness — guarding if severe

Complicated:

abscess — persistent fever, mass
perforation — peritonitis — rigid abdomen — A&E
fistula — colovesical (pneumaturia), colovaginal
stricture, obstruction

Diagnosis

Clinical + CT abdomen/pelvis with contrast — gold standard — shows wall thickening, fat stranding, abscess

Blood tests — CRP, WCC elevated

Colonoscopy — not during acute attack — 6 weeks post-recovery if first episode age >40 — exclude cancer

Treatment

Uncomplicated — outpatient

Antibiotics covering gut flora:

co-amoxiclav
OR ciprofloxacin + metronidazole (if penicillin allergy — local guidance)

Clear liquids → low residue briefly → gradual fibre increase

Paracetamol — avoid NSAIDs early — bleeding risk debate

Some mild cases — antibiotics optional in selected Hinchey 0 — specialist trend — still GP-guided

Complicated — inpatient

IV antibiotics
CT-guided drainage — abscess >3cm often
surgery — Hartmann’s or resection — perforation, failed medical, recurrent

Prevention after recovery

high-fibre diet — 30g/day target
hydration
exercise
healthy weight
** nuts/seeds OK** — myth busted

Diverticulitis vs other causes

Condition	Clue
Appendicitis	RLQ — younger
IBS	Chronic pain, no fever
Bowel cancer	Weight loss, PR bleed — colonoscopy
UTI	Urinary symptoms — colovesical fistula rare

See bowel cancer if alarm features.

Left lower pain + fever over 40 — same-day assessment — CT confirms — most home antibiotics, some need surgery.

Common questions about diverticulitis

What are the symptoms of diverticulitis?: Constant abdominal pain — usually left lower quadrant, fever, nausea, constipation or diarrhoea, bloating, blood in stool sometimes. Pain worsens with movement. Unlike diverticulosis which is silent, diverticulitis is painful and systemic illness.
What causes diverticular disease?: Low-fibre Western diet increases colon pressure causing pouches (diverticulosis) in weak spots of colon wall. Faecal matter trapping in pouches can cause inflammation and bacterial infection (diverticulitis). Age, obesity, smoking, and inactivity increase risk.
How is diverticulitis treated?: Uncomplicated — oral antibiotics (co-amoxiclav or ciprofloxacin + metronidazole), paracetamol not NSAIDs initially, clear fluids progressing to low fibre then high fibre after recovery. Complicated — hospital IV antibiotics, CT scan, abscess drainage, surgery if perforated or recurrent severe episodes.
Should I avoid nuts and seeds with diverticular disease?: No — old advice disproven. Nuts, seeds, and popcorn do not cause diverticulitis. When recovered, high-fibre diet reduces recurrence risk. During acute attack, temporary low-fibre diet as advised.
Does diverticulitis lead to colon cancer?: Diverticular disease does not cause cancer but symptoms overlap — colonoscopy recommended after first episode in age-appropriate patients or if alarm features — to exclude malignancy. Repeated episodes may lower threshold for colonoscopy.

Sources

How we reviewed this page

Medically reviewed by the HealthAnswers UK doctor review panel

First published: 14 June 2026
Medically reviewed: 3 July 2026
Next review due: 3 July 2029 or sooner if NHS or NICE guidance changes

Written by HealthAnswers editorial team. Published by HealthAnswers (Elite Digital AI Solutions Ltd). How we review content · Report a problem with this page