Peppermint oil has been studied for its effects on gastrointestinal symptoms, including belching, primarily because of its antispasmodic properties. The active compounds in peppermint oil, such as menthol, relax the smooth muscles of the gastrointestinal tract by blocking calcium channels. This can decrease spasms in the gut, which are often implicated in symptoms like bloating, discomfort, and excessive belching. Several randomized controlled trials have established the efficacy of enteric-coated peppermint oil in reducing symptoms of irritable bowel syndrome (IBS)—a condition frequently accompanied by belching—by alleviating abdominal pain, distension, and discomfort. However, the majority of clinical studies focus on broader GI symptoms rather than belching as a standalone symptom.

Systematic reviews and meta-analyses indicate a moderate level of evidence for peppermint oil's effectiveness in relieving global IBS symptoms, which often includes belching among other complaints. The evidence for using peppermint oil specifically for belching, independent of other GI symptoms, is less robust but is supported by its mechanism of action and indirect findings from larger IBS studies. Safety concerns exist, especially in individuals with gastroesophageal reflux disease (GERD), as peppermint oil may relax the lower esophageal sphincter and potentially worsen reflux symptoms. Overall, peppermint oil is scientifically validated for functional gastrointestinal disorders, with moderate evidence supporting its use for belching when it is part of a broader symptom complex.