Sometimes the reaction is a bit delayed. I built up to about 5 650mg caps. After about a week, my body adjusted and is producing more of its own HCl. I felt warming more in my intestinal tract than my 'heartburn' area. I also realized early on that I need more alkalizing minerals to ensure that my body was able to alkalize the acidic chyme as it passed thru my GI tract. That made a difference in my 'post-digestion' acidic reactions.