Stomach ulcers are usually caused by an infection of Helicobacter pylori (H. pylori) bacteria, or from taking anti-inflammatory medicines (NSAIDs), such as ibuprofen and aspirin.

These can break down the stomach's defence against the acid it produces to digest food, allowing the stomach lining to become damaged and an ulcer to form.

It’s common to have a H. pylori infection, and it’s usually harmless for most people.

But sometimes it causes ulcers in the stomach (gastric ulcer) or in the duodenum (duodenal ulcer).

It's not clear exactly why some people are more affected than others.

NSAIDs are medicines widely used to treat pain, a high temperature (fever) and inflammation (swelling).

Commonly used NSAIDs include:

• ibuprofen
• aspirin
• naproxen
• diclofenac

Many people take NSAIDs without having any side effects. But there's always a risk the medication could cause problems, such as stomach ulcers, particularly if taken for a long time or at high doses.

You may be advised not to take NSAIDs if you currently have or have had a stomach ulcer. 

Paracetamol can often be used as an alternative painkiller.

There's little evidence that some lifestyle factors, like spicy foods, stress and alcohol, cause stomach ulcers. But they may make your symptoms worse.

It's thought that smoking increases your risk of developing stomach ulcers and may make treatment less effective.