Cimetidine is in a group of medications called histamine type-2-receptor antagonists that block the release of histamine which triggers the secretion of stomach acid. This prevents the indigestion symptoms. Antacids work by neutralizing the stomach acid that is already present. Antacids can relieve the pain of indigestion, but cannot prevent it. Antacids can be taken as needed to treat indigestion symptoms; cimetidine is taken on a routine schedule to prevent symptoms.
Brisochi and Milk of magnesia are common antacids.
Cimetidine, sold under the brand name Tagamet