PreVacid OTC 15mg Capsule 28ctPrevacid 24HR keeps heartburn at bay and off your mind, so you can fully enjoy good meals, good times, and a good night's sleep. Prevacid 24HR is a proton pump inhibitor, or PPI for short, intended for the treatment of frequent heartburn (heartburn that occurs two or more days a week). Prevacid 24HR prevents the acid that causes heartburn, and its uncomfortable symptoms, for a full 24 hours. But how exactly does Prevacid 24HR work? Inside your stomach are millions of little "spigots" called proton pumps. These pumps release the acid your stomach uses to digest food. This is the same acid that can back up into your esophagus and cause heartburn. Prevacid 24HR turns off many of these pumps, preventing the excess acid before it can do you harm.