Famotidine is used to treat and prevent ulcers in the stomach and intestines. This medication is also used to treat Zollinger–Ellison syndrome, erosive esophagitis, and gastroesophageal reflux disease. Famotidine improves the ulcer symptoms such as heartburn and stomach pain. It works by decreasing the amount of acid produced in the stomach. This medicine may also be used to treat other conditions as determined by your doctor.