Diverticula are small pouches in the wall of the large bowel. They become very common with age and usually cause no problems. A high-fibre diet helps, and there is no need to avoid nuts or seeds. If a pouch becomes inflamed (diverticulitis), most episodes settle with simple treatment, but some complications need urgent care.

What do the terms mean?

• Diverticulosis: having pouches (diverticula) without symptoms. It is often found by chance at colonoscopy or on a scan, and becomes more common after age 50
• Diverticular disease: pouches that cause symptoms, such as lower abdominal pain, bloating or a change in bowel habit
• Diverticulitis: inflammation or infection of one or more pouches, causing more severe pain, often with fever
• Diverticular bleeding: bleeding from a small blood vessel next to a pouch

Pouches are most often found in the lower left part of the colon (the sigmoid colon), so pain is usually felt in the lower left abdomen, although they can also occur on the right side. In some Asian populations, especially in East Asia, right-sided pouches are more common, and pain on the right can be mistaken for appendicitis.

What increases the risk?

• Increasing age
• A low-fibre diet and constipation
• Being overweight, and low physical activity
• Smoking
• A diet high in red meat
• Regular use of anti-inflammatory painkillers (such as ibuprofen or diclofenac) and aspirin, which also increase the risk of bleeding
• Long-term steroid tablets or strong opioid painkillers, which are linked to more serious attacks

Looking after yourself

• Eat plenty of fibre: vegetables, fruit, legumes (lentils, chickpeas, beans), oats and wholegrains. Increase it gradually to limit bloating
• A fibre supplement such as psyllium (ispaghula) can help if your diet is low in fibre
• Drink enough fluid, especially in hot weather
• You do not need to avoid nuts, seeds, sesame, popcorn, or fruit with small seeds such as figs or strawberries; large studies have not linked them to diverticulitis or bleeding
• Stay active, keep a healthy weight and stop smoking
• Avoid regular anti-inflammatory painkillers if you can. Do not stop aspirin prescribed for your heart without medical advice

Diverticulitis

Typical symptoms are constant lower abdominal pain, fever, nausea and a change in bowel habit. The diagnosis is often confirmed with blood tests and a CT scan.

• Once a doctor has confirmed mild, uncomplicated diverticulitis, it is often treated at home with paracetamol, fluids and a light diet for a few days
• Antibiotics are not always needed: in selected people with mild, uncomplicated diverticulitis who are otherwise well, recovery is similar without them. Whether you need them is your doctor's decision, based on your scan, tests and general health
• Contact your doctor if you develop fever, worsening pain, or cannot keep fluids down
• Hospital admission is needed for severe pain, high fever, persistent vomiting, or complications
• If you have a weakened immune system (for example from steroids, chemotherapy, transplant or biologic medicines), or other serious illness, seek medical review promptly; you will usually need antibiotics and closer monitoring

After a first episode, a colonoscopy is often advised about 6 to 8 weeks later if you have not had a recent good-quality one, to make sure a bowel cancer, which can look similar on a scan, was not missed.

Possible complications

• Abscess: a collection of pus next to the bowel, sometimes drained with a needle
• Perforation: a hole in the bowel wall causing infection inside the abdomen (peritonitis). This is an emergency and usually needs surgery
• Fistula: an abnormal channel to another organ, most often the bladder, which may cause air or stool in the urine
• Narrowing (stricture) of the bowel after repeated inflammation
• Bleeding: sudden, painless red or maroon blood. It usually stops on its own, but heavy bleeding needs hospital care

Is surgery needed?

Most people never need an operation. Emergency surgery is needed for some complications, such as perforation. Planned surgery may be discussed if attacks are frequent or disabling, or after a complication; the decision is individual rather than based on a fixed number of attacks.

Common questions

This leaflet is general information and does not replace advice from your own doctor. Version 1.0, October 2026. Next review October 2028.