Compare to Prevacid 24 HR active ingredient. up & up Lansoprazole Delayed-Release Capsules 15 mg stops acid production at the source - the pumps that release acid into the stomach. In three clinical studies, lansoprazole 15 mg capsules were shown to be significantly better than placebo in treating frequent heartburn. Taken once a day (every 24 hours), every day for 14 days; may take 1 to 4 days for full effect. Take in the morning before eating. Experience life without heartburn.