Many peptic ulcers are caused by infection with Helicobacter pylori (H. pylori) bacteria. H. pylori live in the mucous lining of the stomach and may cause inflammation that could lead to an ulcer.

The infection may spread through contact with fecal material, which can happen when people do not wash their hands after going to the bathroom. Because of this, a person's risk for getting an infection may increase if a family member also has the infection.¹H. pylori is still common in the United States, especially in people older than age 65. The infection is not very common in people younger than age 20.

Fewer people are getting infected with H. pylori than did in the past. And of the people who are infected with H. pylori, very few will get a peptic ulcer.

Certain factors may make a person who has an H. pylori infection susceptible to developing an ulcer. These factors may include:

• The use of certain medicines, such as aspirin or other nonsteroidal anti-inflammatory drugs (NSAIDs).
• Excessive alcohol use.
• Other illnesses.

People who have had a peptic ulcer and are infected with H. pylori need treatment to cure the infection to lower their risk of developing another peptic ulcer. Treatment with a combination of medicines is highly successful at curing an H. pylori infection.² Sometimes H. pylori bacteria are resistant to certain antibiotics, which can keep the medicine from killing the bacteria.