Bismuth subcitrate potassium is a bismuth-containing compound primarily used in the eradication of Helicobacter pylori infections, which are associated with peptic ulcers and gastritis. It forms a protective coating on the gastric mucosa by complexing with proteins, shielding ulcerated areas from gastric acid and pepsin to promote healing. It also exhibits direct antimicrobial activity against H. pylori, making it a key component in combination therapies (such as triple or quadruple regimens) with antibiotics and proton pump inhibitors. While it may provide some relief from gastrointestinal symptoms, it is not primarily an antacid and does not significantly neutralize stomach acid or reduce acid secretion.