I have had acid reflux for several years now. I was on a prescription for Prilosec before it was OTC. Usually only took a pill when I felt the reflux coming on strong. Over time, it has gotten worse with many reflux attacks daily. Two months ago, I started taking Prilosec OTC every day to see if I could fend it off. It worked great and I rarely felt any reflux all day long. Then, I had three violent episodes of Vertigo....which is similar to being spun around while you are violently seasick and stays like that for about 5 hours. Turns out this is rare but known side-effect of Prilosec. Needless to say, I'm off it now. I am relying on Pepsid AC now which works great but only last for a few hours and gets expensive. I'm planning to try the ACV next.