Colloidal bismuth subcitrate is used in the treatment of Peptic ulcer disease.How Colloidal bismuth subcitrate worksColloidal bismuth subcitrate is believed to work by several methods. First, it increases in mucus glycoprotein secretion and may also bind to the gastric mucus layer to act as a diffusion barrier to HCl. It is also known to have cytoprotective effect and enhances mucosal secretion of prostaglandins and bicarbonate.