Rennie Peppermint tablets provide fast relief from heartburn and indigestion. Wherever you are and whatever you are up to, Rennie is by your side – no matter if it is day or night. Whether you are bothered by acid reflux at work and find it hard to be at your most productive or, like many, have trouble sleeping because of burning sensations that appear at night, the fast-working antacids in Rennie chewable tablets neutralise excess stomach acid to let you relax. The two active ingredients are calcium carbonate and magnesium carbonate.