Peptic ulcer is a disease characterized by painful aches on your stomach lining or on the upper part of your intestine called duodenum. The cause of this can be two things: imbalance of digestive fluids in the stomach or an infection in the duodenum by the bacteria Helicobacter pylori or H. pylori. When you have this bacteria, the doctor would prescribe antibiotic medications to kill it using drugs like amoxicillin, levofloxacin or chlarithromycin. You would also be medicated with a proton pump inhibitor or Pepto-Bismol to reduce stomach fluids.