Stomach ulcers, also known as gastric ulcers, are painful sores that develop in the stomach lining. You get these open sores when the thick layer of mucus that protects your stomach from digestive juices is reduced. Then the digestive acids eat away the tissues that line the stomach, causing an ulcer. Stomach ulcers can become severe if not treated properly.Stomach ulcers can be caused by an infection with the bacterium Helicobacter pylori (H. pylori) or long-term use of nonsteroidal anti-inflammatory drugs (NSAIDs), such as aspirin, ibuprofen, or naproxen. The most common symptom of a stomach ulcer is a burning or gnawing pain in the centre of the abdomen (tummy). But some people may experience other symptoms, such as indigestion, heartburn and feeling sick. The severity of the symptoms depends on the severity of the ulcer. Here are some common signs and symptoms of stomach ulcers. Talk to your doctor if you have any symptoms of a stomach ulcer.