Zero Heartburn for 24 Hours with One Pill a Day Directly blocks many of the active stomach pumps that produce acid before they start Works for 24 hours with one pill a day. It is indicated for a 14-day course of treatment, up to three times a year Unlike many heartburn remedies Prilosec OTC effectively fights heartburn before it begins. It's an over the counter PPI clinically proven to block heartburn for 24 hours. And that means with 1 pill a day for 14 days, you get the relief you need from the pain of frequent heartburn. While taking Prilosec OTC, heartburn won't keep coming back. (It's possible with Prilosec OTC.