Cimetidine is a drug that blocks the production of acid by acid-producing cells in the stomach and can be administered orally, IM or IV.

Cimetidine is used to:

• relieve heartburn associated with acid indigestion and sour stomach
• prevent heartburn brought on by eating or drinking certain foods and beverages

It belongs to a class of drugs called H2 (histamine-2) blockers that also includes ranitidine (Zantac), nizatidine (Axid), and famotidine (Pepcid). Histamine is a naturally-occurring chemical that stimulates cells in the stomach (parietal cells) to produce acid. H2-blockers inhibit the action of histamine on the cells, thus reducing the production of acid by the stomach.

Since excessive stomach acid can damage the esophagus, stomach, and duodenum by reflux and lead to inflammation and ulceration, reducing stomach acid prevents and allows acid-induced inflammation and ulcers to heal. Cimetidine was approved by the FDA in 1977.