Stomach ulcers, also known as peptic ulcers, are a common stomach malady caused by the erosion of the lining of the stomach or small intestine. They can be caused by a variety of factors, including stress, certain medications, and an infection with the bacterium Helicobacter pylori. Symptoms of stomach ulcers include abdominal pain, nausea, vomiting, and loss of appetite. Treatment for stomach ulcers typically involves medications to reduce acid production and antibiotics to treat any underlying infection.