What happens if H. pylori is left untreated?

If left untreated, H. pylori infection can cause chronic gastritis, stomach or duodenal ulcers, and in some cases increase the risk of gastric cancer or lymphoma. Not everyone will develop complications, but those who do may experience severe pain, bleeding, or even life-threatening issues. According to the CDC, people with H. pylori are several times more likely to develop stomach cancer. That’s why timely diagnosis and treatment are crucial, even if symptoms seem mild at first.