Description Ranitidine is a from a group of drugs called Histamine 2 (H2) blockers. Ranitidine works by reducing the amount of acid that is produced in the stomach. Ranitidine is used to help treat and prevent stomach and intestinal ulcers and is also useful in treating indigestion, heartburn, excess stomach acid and Gastro-oesophageal reflux disease (GORD or GERD) commonly known as Acid Reflux.