Too much stress, too much spicy food, and you may be headed for an ulcer — or so the thinking used to go.

Not long ago, the common belief was that peptic ulcers were a result of lifestyle. A great deal has changed. Doctors now know that a bacterial infection or medications, not stress or diet, cause most ulcers of the stomach and upper part of the small intestine. Most ulcers of the esophagus are associated with the reflux of stomach acid.

Peptic ulcers are open sores that develop on the inside lining of your stomach, upper small intestine or esophagus. The most prominent symptom of a peptic ulcer is pain.

Depending on their location, ulcers have different names:

• Gastric ulcer. A peptic ulcer that occurs in your stomach is called a gastric ulcer.

• Duodenal ulcer. An ulcer that develops in your small intestine is named for the section of the intestine where it develops. The most common is a duodenal (doo-o-DEE-nul) ulcer, which develops in the duodenum, the first part of the small intestine.

• Esophageal ulcer. An esophageal ulcer is usually located in the lower section of your esophagus. It's often associated with chronic gastroesophageal reflux disease (GERD).

Peptic ulcers are common. About one in 10 Americans experience a peptic ulcer at some point in their lives. The good news is that, oftentimes, successful treatment of ulcers takes just a few weeks.