The main cause of peptic ulcers is believed to be infection by Helicobacter pylori. Other factors such as smoking, alcohol, poor diet, living habits, medication use, or emotional issues can also play a role. Clinically, these ulcers are often characterized by upper abdominal pain. In the case of gastric ulcers, the pain is primarily in the upper left abdomen or below the sternum, and can manifest as dull pain, blunt pain, or a feeling of distension. This pain is often more apparent after meals, commonly occurring half an hour to an hour after eating, and usually subsides two to three hours later. Duodenal bulb ulcers are characterized by upper abdominal muscular pain, occurring around two centimeters above and to the right of the navel, sometimes accompanied by nighttime pain. If the ulcer is located behind the bulb, back pain can also occur. Peptic ulcers can lead to other complications, such as perforation, bleeding, or even cancer.