The contents of the stomach are acidic. The acid helps to protect the body from infection and helps break down the food that is eaten. The lining of the stomach and duodenum is covered in mucus (a thick, smooth fluid), which protects it from this acid. An ulcer can result when the stomach produces excess acid or there is insufficient mucus to protect the lining from damage.

There are several factors that increase a person's risk of getting a peptic ulcer:

• infection with bacteria called Helicobacter pylori (H. pylori) - this is almost always present in people with ulcers, although it's also found in the stomachs of many people without ulcers or indigestion symptoms
• regularly taking certain medicines, particularly aspirin and other non-steroidal anti-inflammatory drugs (NSAIDs) such as ibuprofen, naproxen and diclofenac
• smoking
• drinking alcohol in excess

Occasionally, a gastric ulcer may develop within a cancer in the lining of the stomach.

Some people with peptic ulcers have no symptoms. However, many people have abdominal pain, usually just below the chestbone.

A gastric ulcer typically causes a sharp pain in the stomach soon after eating, whereas the pain of a duodenal ulcer is typically relieved by eating, or by drinking milk. Other symptoms may include:

• belching
• general discomfort in the stomach
• loss of appetite or, rarely, increased appetite
• nausea
• vomiting
• loss of weight

Tests are carried out to see if there is infection with H. pylori, to diagnose gastric or duodenal ulcers, and to rule out other conditions such as stomach cancer.

H. pylori tests - someone with suspected peptic ulcer is likely to be tested for H. pylori. This is done with either a breath or blood test. For the breath test, you are given a harmless substance to swallow. The substance is broken down if H. pylori is present, to produce a gas that is detected in the breath. This test is also used to check whether treatment has eradicated H. pylori.

Barium swallow - this involves swallowing a drink containing barium, which shows up white on X-rays. The barium coats the lining of the stomach and duodenum, and X-rays are taken to show an outline. These may show an ulcer.

Gastroscopy - a tube (endoscope) containing a fibre-optic cable is passed through the mouth and into the stomach. The doctor can see the lining of the stomach through the tube, and can take a sample of the stomach lining with an instrument that is passed down through the tube. This sample is tested for H. pylori and examined under a microscope (biopsy) to check whether cancer is present.

A number of lifestyle changes may reduce the symptoms of a peptic ulcer, and speed up healing.

• avoid food and drink that seems to cause more severe symptoms such as spicy foods, coffee and possibly alcohol,
• stop smoking,
• lose excess weight if overweight,
• stop taking NSAIDs and use paracetamol instead. If this is not possible, contact your GP for advice. For people with ulcers, a type of NSAID called a cyclo-oxygenase-2 selective inhibitor (cox-2-inhibitor, eg rofecoxib) may cause less stomach irritation.

In addition to recommending lifestyle changes, if applicable, your doctor may prescribe a course of tablets to reduce the amount of acid produced by the stomach.

Two main groups of medicine are available to do this. The first of these are called H2-antagonists. Examples include ranitidine (eg Zantac) and cimetidine (eg Tagamet). The second group are known as proton pump inhibitors, and tend to have a more powerful effect in reducing the production of stomach acid. Examples include omeprazole (eg Losec) and lansoprazole (Zoton).