Magnesium Hydroxide: Uses, Alternatives, and What You Need to Know

When you reach for something to calm an upset stomach or ease constipation, you might be holding magnesium hydroxide, a mild base used in over-the-counter antacids and laxatives. Also known as milk of magnesia, it’s one of the oldest and most trusted remedies for digestive discomfort. Unlike strong acid blockers, it doesn’t shut down stomach acid production—it just neutralizes what’s already there. That makes it faster acting for heartburn and gentler on your system than some prescription options.

Magnesium hydroxide doesn’t just treat heartburn. It’s also a go-to for occasional constipation because it pulls water into the intestines, softening stool and triggering natural movement. That’s why you’ll find it in many daily digestive aids. But it’s not just a quick fix—it’s part of a broader group of compounds used to balance gut health. Related to magnesium supplements, a broad category of minerals used for muscle function, nerve signaling, and sleep, magnesium hydroxide delivers the same mineral but in a form designed for immediate digestive impact. It’s different from magnesium citrate or magnesium glycinate, which are better for long-term deficiency, but perfect for when you need relief now.

People often compare it to antacids, like calcium carbonate or aluminum hydroxide, which also neutralize stomach acid, but magnesium hydroxide tends to work faster and has a built-in laxative effect. That’s a plus if you’re dealing with both acid reflux and constipation, but a drawback if you’re sensitive to loose stools. It’s also less likely to cause rebound acidity than some proton pump inhibitors, which is why many use it as a short-term solution instead of daily medication.

While it’s widely available without a prescription, it’s not for everyone. People with kidney problems should avoid it—your kidneys help remove excess magnesium, and if they’re not working well, it can build up. And while it’s safe for most adults, using it daily for more than a week without checking in with a doctor isn’t recommended. It’s a tool, not a long-term fix.

What you’ll find below is a collection of real comparisons and practical guides—like how magnesium hydroxide stacks up against other digestive aids, when to choose it over alternatives, and how it fits into broader health routines. These aren’t marketing pieces. They’re honest, evidence-based breakdowns from people who’ve tried these options and want to know what actually works.