Sodium hydrogen carbonate, or baking soda, functions as an antacid by neutralizing excess stomach acid. When ingested, it reacts with the acidic gastric contents, producing carbon dioxide, water, and salt. This reaction increases the pH of the stomach, providing relief from symptoms of indigestion, heartburn, or acid reflux. The carbon dioxide produced can also promote burping, helping to expel gas. While it offers temporary relief, excessive or frequent use is cautioned due to the sodium content, and individuals with certain medical conditions should consult healthcare professionals before using sodium hydrogen carbonate as an antacid.