Luo San (often referring to a traditional Chinese medicinal powder or a specific herbal preparation) is primarily justified for use in treating belching by traditional medicinal practices. In traditional Chinese medicine (TCM), belching is often interpreted as a symptom of disharmony in the digestive system, particularly involving "Qi stagnation" or disturbances in the Stomach and Spleen. Luo San and similar formulas are believed to help "regulate Qi," reduce stagnation, and harmonize the stomach, thereby alleviating symptoms such as belching, bloating, and fullness.

Historical records and materia medica texts from TCM, such as the Compendium of Materia Medica and other classical sources, document the use of Luo San and related powders for digestive complaints, including belching (also described as "ge qi" or "ge da qi" in Chinese). The formulation may include ingredients like citrus peel, pinellia, or other herbs that are traditionally thought to move Qi and resolve dampness.

However, the evidence supporting Luo San’s efficacy is based on traditional use and theoretical frameworks unique to TCM rather than on modern scientific research or clinical trials. There is limited or no robust scientific validation published in peer-reviewed literature specifically regarding Luo San for belching as understood in Western medicine. As such, its use is rated at 2 on the evidence scale, reflecting consistent traditional use but a lack of high-quality scientific evidence.