Prevacid 24HR keeps heartburn pain 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 (PPI) 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.