Famotidine, the active ingredient in Pepcid and Pepcid AC, is an H2 blocker that reduces the amount of acid the stomach produces. It is commonly used for the short-term relief of heartburn, acid indigestion, and symptoms associated with excess stomach acid. Pepcid Duo combines famotidine with calcium carbonate, offering a dual action that neutralises existing acid while also reducing further acid production. Pepcid differs from proton pump inhibitors such as omeprazole in how it works and how quickly it acts. H2 blockers like famotidine typically take effect within 15 to 30 minutes, while PPIs generally require regular dosing over several days to reach full effect. Neither is universally preferable; the right choice depends on symptom frequency, severity, and personal history. Ronaghan's Pharmacy stocks Pepcid products for collection or delivery to addresses across Ireland. As with all non-prescription medicines, always read the patient information leaflet before use and speak to your pharmacist if symptoms persist or you are taking other medicines. For a wider range of stomach and digestive products, browse the full Digestive Health category.