Magnesium hydroxide and sodium bicarbonate are the two main over-the-counter antacid ingredients that contain neither calcium nor aluminum.
For the full breakdown, see our best Antacid Without Calcium guide.
A drugstore shelf looks like a wall of identical boxes until you flip one over and read the Active ingredient panel. That panel is what separates the antacids without calcium or aluminum from everything else: magnesium-based products, mostly magnesium hydroxide, and sodium bicarbonate. Brand names tell you nothing, and plenty of bottles that look like a plain magnesium tablet also carry calcium carbonate or aluminum hydroxide.
Two things decide whether a product fits what you need. The ingredient list has to be read on the package itself, every time you buy. The daily limit matters just as much, because the two families behave very differently — one turns into a laxative at higher doses, and the other is a sodium load.
Which Antacids Contain No Calcium Or Aluminum?
Two ingredient families meet the requirement outright: magnesium products and sodium bicarbonate. FDA’s OTC antacid monograph also lists magnesium oxide, magnesium carbonate, magnesium glycinate, and magnesium trisilicate as permitted antacid ingredients, and none of those contains calcium or aluminum.
A DailyMed label for a magnesium hydroxide suspension shows how the numbers look in practice: 400 mg of magnesium hydroxide per 5 mL, with about 165 mg of elemental magnesium and 2 mg of sodium in that same 5 mL. The product is labeled as both an antacid and a saline laxative, which is why loose stools are the side effect people notice first.
The ingredient names to reject are just as specific. Rolaids Ultra Strength 1200 carries 1,000 mg of calcium carbonate and 200 mg of magnesium hydroxide per chewable tablet. A DailyMed-listed Supreme Antacid suspension holds 400 mg of calcium carbonate and 135 mg of magnesium hydroxide per 5 mL. A standard aluminum-magnesium suspension runs 400 mg of aluminum hydroxide, 400 mg of magnesium hydroxide, and 40 mg of simethicone per 10 mL. None of those three passes, even though magnesium appears on two of the labels.
| Antacid Option | Active Ingredient Per Dose | What Matters Most |
|---|---|---|
| Magnesium hydroxide suspension | 400 mg per 5 mL | Also a saline laxative; diarrhea is the usual sign of too much |
| Magnesium oxide | Permitted by FDA’s OTC antacid monograph | Calcium-free and aluminum-free when it is the only active ingredient |
| Magnesium carbonate | Permitted by FDA’s OTC antacid monograph | Common in chewables; check for added calcium carbonate |
| Magnesium trisilicate | Permitted by FDA’s OTC antacid monograph | Rare in US products, so it is easy to overlook |
| Sodium bicarbonate | Varies by product and dose form | Not low-sodium; daily limits are 200 mEq under age 60 and 100 mEq at 60 and older |
| Rolaids Ultra Strength 1200 | Calcium carbonate 1,000 mg + magnesium hydroxide 200 mg per tablet | Fails the requirement — calcium is an active ingredient |
| Supreme Antacid suspension | Calcium carbonate 400 mg + magnesium hydroxide 135 mg per 5 mL | Fails the requirement — calcium is an active ingredient |
| Aluminum-magnesium suspension | Aluminum hydroxide 400 mg + magnesium hydroxide 400 mg + simethicone 40 mg per 10 mL | Fails the requirement — aluminum is an active ingredient |
If comparing labels on paper is the part you would rather skip, our tested roundup of calcium-free antacids narrows the shelf to the bottles that already passed the check.
Calcium-Free And Aluminum-Free Antacids: Doses And Daily Limits
A magnesium hydroxide suspension is labeled for 1 to 3 teaspoons with water, up to four times a day, with a hard ceiling of 12 teaspoons in 24 hours — and the label says not to stay at the maximum dose for more than two weeks.
Those numbers belong to that one product. A teaspoon of one liquid is not a teaspoon of another, because concentrations differ, so the package directions are the only dose that applies to the bottle in your hand.
Sodium bicarbonate works under a different set of rules. FDA’s OTC antacid monograph recognizes sodium bicarbonate as an antacid ingredient and caps daily intake at 200 mEq of sodium and bicarbonate for people under 60, dropping to 100 mEq at age 60 and older. That is a real sodium load on a salt-restricted diet, and the age-based ceiling is why the monograph does not treat bicarbonate as a casual repeat dose.
Who Needs A Pharmacist’s Input Before Dosing
Kidney disease is the biggest stop sign for magnesium antacids, because damaged kidneys clear magnesium slowly and repeated doses raise the risk of magnesium toxicity. Sodium bicarbonate carries its own list: a sodium-restricted diet, high blood pressure, heart failure, and kidney disease all make the extra sodium a problem worth a professional opinion first.
Antacids also change how well some oral medicines are absorbed. The right gap between an antacid and another drug depends entirely on which drug it is, and the label does not print one universal interval — a pharmacist can set it for you in about a minute.
Children under 12, pregnancy and breastfeeding, unexplained stomach pain, vomiting, black stools, and trouble swallowing all call for guidance before the first dose. Neither family is a long-term answer for reflux that keeps returning, either; symptoms that persist deserve a diagnosis rather than another bottle.
Six Checks Before The First Dose
- Read the Active ingredient panel on the actual package, not the front of the box.
- Cross off calcium carbonate, calcium phosphate, aluminum hydroxide, aluminum carbonate, magaldrate, and aluminum-magnesium complexes.
- Confirm a magnesium choice lists magnesium hydroxide or another permitted magnesium ingredient with no calcium or aluminum beside it.
- For sodium bicarbonate, total the day’s amount and stay inside the limits for your age.
- Use the exact amounts printed on that product’s label; teaspoon doses are not interchangeable between brands.
- Ask a pharmacist if you have kidney disease, a sodium restriction, other medicines, a pregnancy, or symptoms past the labeled treatment window.
Common Questions
Can a magnesium antacid be taken every day?
Short-term daily use is what the label covers: up to four doses a day, no more than 12 teaspoons in 24 hours, and never the maximum dose for longer than two weeks. Magnesium hydroxide is also a saline laxative, so diarrhea is the usual sign you have taken too much. Reflux that returns after treatment ends needs a diagnosis, not another bottle.
Can an antacid interfere with my other medicines?
Yes. Antacids can change how well some oral medicines are absorbed, and the correct separation window depends on the specific drug involved. The product label does not provide one universal interval, so ask a pharmacist how long to wait between the antacid and each of your prescriptions. Bring the list — the answer takes a minute.
Does seeing magnesium on a label mean the product has no calcium?
No. Combination products are common, and some pair magnesium hydroxide with calcium carbonate or aluminum hydroxide in the same tablet or suspension, so the word “magnesium” proves nothing on its own. The only reliable check is the Active ingredient panel on the package in front of you.
Sources
- U.S. Food and Drug Administration. “OTC Monograph M001: Antacid Products for OTC Human Use” Lists the permitted antacid ingredients and the daily sodium and bicarbonate limits by age.
- DailyMed (National Library of Medicine). “Magnesium hydroxide oral suspension — OTC label” Supports the 400 mg per 5 mL concentration, the elemental magnesium figure, and the adult dosing limits.