The introduction of eradication therapy means that complications of stomach ulcers related to H. pylori infections are now uncommon.

Complications are more common with stomach ulcers associated with the use of non-steroidal anti-inflammatory drugs (NSAIDs). This is because these types of ulcers do not always cause obvious symptoms, so are left untreated.

It is estimated that around 1 in 50 people with a NSAID-related stomach ulcer will develop a complication.

Internal bleeding

Internal bleeding is the most common complication of stomach ulcers. Internal bleeding can occur when an ulcer develops at a site of a blood vessel. You are at an increased risk of bleeding if you:

• are on continued use of non-steroidal anti-inflammatory drugs (NSAIDs)
• are 60 years old or over

Depending on the location and type of blood vessel, you may have long-term bleeding that could lead to anaemia (where the body has a lack of oxygen-carrying red blood cells).

Symptoms of anaemia include:

• fatigue
• breathlessness
• pale skin
• irregular heartbeats

Alternatively, the bleeding can be rapid and massive, causing you to vomit blood or pass stools that are black and tar-like.

An endoscopy is needed to identify the cause of this sort of internal bleeding. Often bleeding can be stopped by treatment performed through the endoscope.

Injections of proton pump inhibitors (PPIs) are also given around the site of the bleeding. Lowering the amount of acid around the site is thought to make the blood more likely to clot, which helps stop the bleeding.

Massive bleeding can be treated using blood transfusions to replace any blood loss. Surgery is occasionally needed to repair the blood vessels.

Perforation

A rarer complication of stomach ulcers is the lining of the stomach splitting open (a perforation). It affects around 1 in 350 people with a stomach ulcer.

Perforation can be very serious because it enables the bacteria that live in your stomach to escape and infect the lining of your abdomen (peritoneum). This is known as peritonitis.

The most common symptom of peritonitis is sudden abdominal pain, which gets steadily worse.

In peritonitis, an infection can rapidly spread into the blood (sepsis) before spreading to other organs. This carries the risk of multiple organ failure, and can be fatal if left untreated.

Peritonitis is a medical emergency that requires admission to hospital. Read more about treating peritonitis.

Gastric outlet obstruction

In some cases, an inflamed or scarred stomach ulcer can obstruct the normal passage of food through your digestive system. This is known as gastric outlet obstruction.

Gastric outlet obstruction is relatively uncommon. Each year it affects around 1 in 1,000 people with a stomach ulcer.

Symptoms of gastric outlet obstruction include:

• repeated episodes of vomiting, with large amounts of vomit that contain undigested food
• a persistent feeling of bloating or fullness
• feeling very full after eating less food than usual
• unexplained weight loss

An endoscopy will confirm the type and site of the obstruction. If the obstruction is caused by inflammation, PPIs or H2-receptor antagonists can be used to help reduce it.

If the obstruction is caused by scar tissue, surgery may be needed to treat it, although sometimes it can be treated by passing a small balloon through an endoscope and inflating it to widen the site of the obstruction.

In more severe cases of scarring, it may be necessary to surgically remove the affected section of stomach, before reattaching the remainder of the stomach.