I began using Prevacid when it was still available only by prescription. It worked wonders. I could take one pill and have no heartburn for three to four days. It's still that great, only now it's available over the counter. There are several over the counter products right now that fight acid reflux and heartburn, but in my opinion, none can hold a candle to this one. Zegerid, Prilosec, and even the others like Zantac are useless in comparison. The most recent medication my doctor prescribed for this, aciphex, doesn't even come close to Prevacid's efficacy. When I first started taking it, it would cause my to have diarrhea, but only once a day, and that would be it. Just seemed to loosen my stools a little. Other than that, I never experienced a single side effect. In some ways, it's unfortunate that it's over the counter because I can't get insurance to pay for it now, but it's well worth the money to have it, and there are coupons available quite often in the Sunday papers, which really helps with the price. As far as I'm concerned, this is the ONLY product that actually works for me.