H2 Blockers: What They Are, How They Work, and What You Need to Know

When your stomach makes too much acid, it can cause heartburn, ulcers, or acid reflux. That’s where H2 blockers, a class of medications that reduce stomach acid production by blocking histamine H2 receptors in the stomach lining. Also known as histamine H2 receptor antagonists, they’ve been used for decades to give relief when antacids aren’t enough. Unlike proton pump inhibitors (PPIs), which shut down acid production more completely, H2 blockers work faster but don’t last as long—making them ideal for quick relief or nighttime dosing.

Common H2 blockers include famotidine, a widely used H2 blocker sold as Pepcid, known for its long duration and low risk of side effects, ranitidine, once the most popular H2 blocker, now withdrawn in many countries due to contamination concerns, and cimetidine, the first H2 blocker ever developed, still available but known for more drug interactions. These drugs don’t cure the root cause of acid problems—they just turn down the volume on stomach acid. That’s why they’re often paired with lifestyle changes like avoiding spicy food, eating smaller meals, or not lying down right after eating.

People often turn to H2 blockers when they’ve tried antacids and still feel that burning sensation. They’re also used for healing ulcers, preventing stress ulcers in hospitals, and managing Zollinger-Ellison syndrome—a rare condition where tumors cause extreme acid production. But they’re not for everyone. If you’re on kidney meds, have liver disease, or take other drugs like warfarin or antifungals, H2 blockers can interact. Famotidine is generally the safest choice today, especially since ranitidine was pulled from shelves. And while PPIs get more attention, H2 blockers still hold their ground: they’re cheaper, have fewer long-term risks, and work great when taken before bedtime to stop nighttime acid.

What you’ll find in this collection are real-world guides on how H2 blockers fit into the bigger picture of digestive health. You’ll see how they relate to acid reflux treatments, why some people switch from PPIs to H2 blockers, how drug interactions can sneak up on you, and what alternatives exist when these meds stop working. There’s no fluff—just clear, practical info on what works, what doesn’t, and what you need to ask your doctor before taking another pill.