Most stomach and duodenal ulcers have one of two causes: infection with H. pylori bacteria, or anti-inflammatory painkillers. Treating the cause heals the ulcer and usually stops it coming back.

What is it?

A peptic ulcer is an open sore in the lining of the stomach (gastric ulcer) or the first part of the small bowel (duodenal ulcer). The lining is normally protected from stomach acid. When that protection is weakened, acid damages the lining and an ulcer forms.

What causes it?

• Helicobacter pylori (H. pylori): a common bacterial infection of the stomach, usually picked up in childhood. Many people carry it without symptoms, but it is a leading cause of ulcers and, over many years, a risk factor for stomach cancer
• Anti-inflammatory painkillers (NSAIDs) such as ibuprofen, diclofenac, naproxen and aspirin, even at low dose. The risk is higher with age over 65, a previous ulcer, or when taken with steroids or blood thinners
• Smoking slows healing and increases the risk
• Stress and spicy food do not cause ulcers on their own, although they can make symptoms feel worse

Symptoms

• Burning or gnawing pain in the upper abdomen, sometimes worse when hungry or at night
• Indigestion, bloating or feeling full quickly
• Nausea
• Some ulcers cause no symptoms until a complication such as bleeding occurs, especially in people taking anti-inflammatory painkillers

Tests

• H. pylori testing: a breath test, a stool antigen test, or biopsies taken at gastroscopy. Blood antibody tests are less reliable because they can stay positive after the infection has gone
• For an accurate breath or stool test, stop proton pump inhibitors for 2 weeks and antibiotics for 4 weeks beforehand, unless your doctor advises otherwise
• Gastroscopy if you have warning symptoms, are older, or if the diagnosis is uncertain. A stomach ulcer is usually checked again with a repeat gastroscopy to confirm healing

Treatment

If H. pylori is found, it is treated with a combination of two or three antibiotics and an acid-reducing medicine, usually for 14 days. Taking every dose for the full course is the single most important factor in success. Side effects such as a metallic taste or loose stools are common and usually mild. If your treatment contains bismuth, your stools will turn black; this is expected and harmless.

A test to confirm that the infection has gone should be done at least 4 weeks after finishing treatment. If the first course fails, a different combination is used.

If an anti-inflammatory painkiller is the cause, it should be stopped where possible. If you need it, or need aspirin for your heart, your doctor will add stomach protection. Do not stop aspirin or blood thinners prescribed for your heart without medical advice.

A proton pump inhibitor is given for several weeks to heal the ulcer.

Possible complications

• Bleeding, which may show as vomiting blood or black, tarry stools
• Perforation (a hole through the wall), causing sudden severe abdominal pain
• Scarring that narrows the outlet of the stomach, causing repeated vomiting

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.