An ulcer is a pathological defect in skin or other epithelium, caused by inflammation secondary to infection, loss of blood supply, failure of venous return or cancer. Various skin lesions can cause ulcers, including infection, arterial disease, varicose veins, and skin cancer. Aphthous ulcers in the mouth are painful epithelial lesions of unknown origin. Peptic ulcers include gastric and duodenal ulcers, although the two have different causes; they may cause characteristic pain, acute hemorrhage, or lead to performation and peritonitis. Severe scarring or edema around the pylorus may cause stenosis with vomiting and stomach distension. Antacids, rest, stopping smoking, and licorice derivatives may help peptic ulcer but surgery may also be needed.