A peptic ulcer is an ulcer of one of those areas of the gastrointestinal tract that are usually acidic.
A more general term, peptic ulcer disease (PUD), is also in use.
Most ulcers are associated with Helicobacter pylori, a spiral-shaped bacterium that lives in the acidic environment of the stomach.
Ulcers can also be caused or worsened by drugs such as Aspirin and other NSAIDs.
Contrary to general belief, more peptic ulcers arise in the duodenum (first part of the small intestine, just after the stomach) than in the stomach.
About 4 % of stomach ulcers are caused by a malignant tumour, so multiple biopsies are needed to make sure.
Duodenal ulcers are generally benign.