Famotidine, sold under the trade name Pepcid among others is a histamine H2 receptor antagonist that inhibits stomach acid production. It is commonly used in the treatment of peptic ulcer disease and gastroesophageal reflux disease.
Unlike cimetidine, the first H2 antagonist, famotidine has no effect on the cytochrome P450 enzyme system, and does not appear to interact with other drugs.
It was discovered in 1979.