Answer
It neutralises stomach acid, increasing stomach pH and easing acid-related burning or discomfort. It does not correct the underlying cause of recurrent heartburn.
Sources for this answer
- Calcium Carbonate 500mg Chewable Tablets — Current selected SmPCemc · Summary of Product Characteristics
- Rennie 750mg Medicated Chewing Gum — Current selected SmPCemc · Summary of Product Characteristics
- NHS