An ulcer is damage to the inner lining (the mucosa) of the stomach or the upper part of the intestine (duodenum). A bacterium, Helicobacter pylori, is the main cause of ulcers in this area.

Abdominal pain is the main symptom. It may awaken you at night, occur 2-3 hours after you eat, or get worse if you skip a meal. The pain may be relieved by antacids or milk.

Other possible symptoms include:
Nausea, vomiting
Weight loss
Fatigue
Heartburn, indigestion, belching
Chest pain
Vomiting blood
Bloody or dark tarry stools

It is important to note that you may have no symptoms at all from an ulcer.