Peptic ulcers can occur in the duodenum and stomach. Duodenal ulcers are in the duodenum, usually near the pyloric sphincter. Approximately 80% of all peptic ulcers are duodenal ulcers. The most common contributing factor to developing duodenal ulcers is the over secretion of gastric juices relative to the degree of mucous and alkaline protection of the small intestine. People who experience severe anxiety over a long period are the most prone to developing duodenal ulcers. They often have a rate of gastric secretion between meals that is as much as 15 times the normal amount. Gastric ulcers are in the stomach In some patients with gastric ulcers, normal or even low levels of gastric acid secretion often occur. The stomachs of these patients, however, have reduced resistance to their own acid, Such inhibited resistance can result from excessive ingestion of alcohol or aspirin, which directly damages the mucosa. Reflux of duodenal contents into the stomach can also cause gastric ulcers. In this case, bile, which is present in the reflux, gas a detergent effect that reduces gastric mucosal resistance to acid, as well as to bacteria. Prostaglandins normally stimulate increased mucus production and inhibit acid production in the stomach. Some drugs used to treat arthritis inhibit prostaglandin synthesis, which reduces inflammation. A side effect of taking prostaglandin inhibitors is irritation and ulcers of the mucosa caused by decreased mucus production and increased acid production.