Sulfur burps, or foul-smelling burps, are usually associated with diet, but they can also be caused by gastrointestinal problems, such as gastroesophageal reflux disease (GERD), gastritis, or peptic ulcers, as well as small intestinal bacterial overgrowth (SIBO) and constipation.
When gastrointestinal problems are present, foul-smelling burps are also commonly accompanied by other symptoms, such as nausea, vomiting, abdominal pain, bloating, or simply a feeling that the stomach is very full.
Especially for people over 60, or when symptoms such as weight loss or persistent vomiting are present and/or there is a family history of stomach cancer, a doctor may recommend tests such as an upper endoscopy to better evaluate the underlying cause.