Magnesium Hydroxide: What It Is and How It Helps You

If you’ve ever taken milk of magnesia for heartburn or constipation, you’ve used magnesium hydroxide. It’s a simple mineral that works as an antacid to neutralize stomach acid and as a gentle laxative to draw water into the bowels. Because it does two jobs, many people keep it handy for occasional upset stomachs or occasional constipation.

How to Use Magnesium Hydroxide Safely

For heartburn, the usual adult dose is 1 to 2 teaspoons (about 5‑10 ml) of the liquid after meals. If you prefer tablets, follow the label—typically 2‑4 tablets every 6‑8 hours, not exceeding 6 g in 24 hours. When you need a laxative effect, the dose is a bit higher: 2‑4 teaspoons (10‑20 ml) once a day, usually before bedtime, and you should only use it for a few days in a row.

Always take magnesium hydroxide with plenty of water. The extra fluid helps the mineral work faster and reduces the chance of feeling bloated. If you’re pregnant, nursing, or have kidney disease, check with a doctor first—your body may handle the mineral differently.

Potential Side Effects and When to Stop

Most people tolerate magnesium hydroxide well, but a few issues can pop up. Common side effects include mild diarrhea, stomach cramps, or a chalky taste. If you get a persistent watery stool, stop the product; you’re probably taking too much. Rarely, an allergic reaction can cause rash, itching, or swelling—seek medical help right away.

Because magnesium can affect other meds, watch for interactions. Antacids can lower the absorption of certain antibiotics (like tetracycline) and heart medicines (like digoxin). If you’re on these drugs, give a 2‑hour gap between them and magnesium hydroxide.

Kidney problems are another red flag. The kidneys filter excess magnesium, so if they’re not working well, magnesium can build up and cause nausea, low blood pressure, or irregular heartbeat. In such cases, a doctor may suggest a different remedy.

When you’re done with a course, you don’t need a taper—magnesium hydroxide clears quickly from the body. Just resume normal hydration and a balanced diet.

Buying Magnesium Hydroxide: What to Look For

Whether you shop online or at a pharmacy, check the label for purity and concentration. Look for products that list “magnesium hydroxide” as the active ingredient and avoid extra fillers like artificial colors or flavors.

Price matters, but the cheapest option isn’t always the best. Compare the cost per gram of magnesium hydroxide to find a fair deal. Reputable brands often have third‑party testing, so you know the product is what it claims to be.

If you buy online, make sure the site is vetted—look for SSL security, clear contact info, and customer reviews. A legit pharmacy will ask for a prescription for higher‑strength formulas and never pressure you to buy in huge bulk without a reason.

Store the product in a cool, dry place and keep the container tightly sealed. The shelf life is usually two years, but check the expiration date before you use it.

Magnesium hydroxide is a handy, inexpensive tool for occasional heartburn or constipation. Use the right dose, watch for side effects, and pick a trustworthy brand, and you’ll have a reliable backup for those pesky digestive moments.