H2 blockers reduce stomach acid by blocking one of the key signals that tells the stomach to make acid: histamine. Medications like famotidine, also known as Pepcid, block H2 receptors on parietal cells in the stomach. When histamine can’t activate those receptors, the stomach produces less acid. That’s why H2 blockers can help with heartburn, acid reflux, and ulcers — especially when symptoms happen at night. Simple idea: H2 blockers reduce acid by blocking histamine’s acid-producing signal. #H