Famotidine, sold under the brand name Pepcid among others, is a histamine H₂ receptor antagonist medication that decreases stomach acid production. It is used to treat peptic ulcer disease, gastroesophageal reflux disease, and Zollinger-Ellison syndrome. It is taken by mouth or by injection into a vein. It begins working within an hour.Common side effects include headache, intestinal upset, and dizziness. Serious side effects may include pneumonia and seizures. Read More