Tagamet, Generic Tagamet, Cimetidine is in a class of drugs called histamine receptor antagonists and works by decreasing the amount of acid the stomach produces.

Cimetidine is used to treat and prevent ulcers in the stomach and intestines.

Cimetidine is also used to treat conditions in which the stomach produces too much acid and conditions in which acid comes up into the esophagus and causes heartburn, such as gastroesophageal reflux disease (GERD).