Ulcers of the stomach or duodenum – occur when the balance of acid in the gastric juices is upset.
Stomach ulcers, also known as gastric ulcers, are open sores that develop on the lining of the stomach.

Ulcers can also occur in part of the intestine just beyond the stomach – these are known as duodenal ulcers.

Both stomach and duodenal ulcers are sometimes referred to as peptic ulcers. Here the term “stomach ulcer” will be used, although the information applies equally to duodenal ulcers.