Comprehensive medication guide to Aluminum Hydroxide/Magnesium Hydroxide including estimated pricing, availability information, side effects, and how to find it in stock at your local pharmacy.
Estimated Insurance Pricing
Aluminum hydroxide/magnesium hydroxide is an OTC product and generally not covered by standard health insurance or Medicare Part D. FSA and HSA funds may be used without a prescription. Some Medicare Advantage plans include OTC allowances covering antacids.
Estimated Cash Pricing
$8–$15 retail for a 355mL bottle at most pharmacies; as low as $6–$7 with GoodRx coupon for a generic suspension.
Medfinder Findability Score
92/100
On this page
Aluminum hydroxide and magnesium hydroxide are two antacid compounds combined in a single OTC product. Together, they neutralize stomach acid to relieve heartburn, acid indigestion, sour stomach, and upset stomach. This combination antacid is available under brand names including Mylanta and as store-brand generics at virtually every major pharmacy chain in the United States.
The brand-name Maalox has been discontinued in the U.S. market, but the active ingredients in Maalox — aluminum hydroxide and magnesium hydroxide — remain widely available as generics. This medication is not a controlled substance and does not require a prescription. It is approved by the FDA for OTC antacid use and may also be prescribed for clinical use in patients with peptic ulcer disease, gastritis, esophagitis, and hiatal hernia.
Common formulations include regular strength (200mg aluminum hydroxide + 200mg magnesium hydroxide per 5mL) and maximum strength (400mg + 400mg per 5mL). Many products also include simethicone (20mg or 40mg per 5mL) for additional gas relief. The British Pharmacopoeia recognizes the combination as co-magaldrox.
We have a 99% success rate finding medications, even during nationwide shortages.
Need this medication?
Aluminum hydroxide and magnesium hydroxide are alkaline (basic) compounds that directly neutralize hydrochloric acid (HCl) in the stomach through acid-base chemistry. When swallowed, they react with stomach acid to form aluminum chloride and magnesium chloride plus water, raising gastric pH and reducing the burning sensation associated with acid reflux and heartburn.
The combination is formulated specifically because the two components complement each other. Magnesium hydroxide raises gastric pH rapidly but has a shorter duration of action. Aluminum hydroxide works more slowly but provides a longer-lasting effect. Together, they deliver both fast onset and sustained acid neutralization.
The GI side effects of the two components also balance each other: aluminum hydroxide alone causes constipation, while magnesium hydroxide alone tends to cause loose stools. In combination, these effects largely offset, resulting in a more neutral bowel impact than either ingredient used alone. Relief typically begins within 5-15 minutes and lasts 30 minutes to 2 hours.
200 mg/200 mg per 5 mL — oral suspension (regular strength)
Standard adult dose: 10-20 mL (2-4 tsp) up to 4 times daily between meals and at bedtime. Max 80 mL/day.
400 mg/400 mg per 5 mL — oral suspension (maximum strength)
Standard adult dose: 10-20 mL (2-4 tsp) up to 4 times daily between meals and at bedtime. Max 60 mL/day.
200 mg/200 mg per tablet — chewable tablet
Chew 2-4 tablets up to 4 times daily between meals and at bedtime. Do not swallow whole. Follow with water.
Aluminum hydroxide/magnesium hydroxide is one of the most widely available OTC medications in the United States. As of 2026, there is no FDA-declared shortage. Multiple manufacturers produce generic versions and they are carried by virtually every major pharmacy chain, grocery store pharmacy section, and online retailer.
The main availability challenge patients encounter is finding a specific brand or formulation. The brand-name Maalox has been discontinued in the U.S., and Mylanta liquid suspension may not be stocked at every pharmacy — particularly smaller or independent locations. Patients who need the liquid suspension formulation will have the best luck at larger chain pharmacies or through online ordering.
If you're having trouble finding the right formulation at your local pharmacy, medfinder can call pharmacies near you to find which ones have it in stock and text you the results — saving you from making multiple calls or unnecessary trips.
Aluminum hydroxide/magnesium hydroxide is not a controlled substance and does not require a prescription. However, any licensed healthcare provider can write a prescription for it if clinically indicated or needed for documentation purposes.
Providers who commonly recommend this antacid include:
For uncomplicated heartburn, telehealth visits are an option if patients need clinical guidance on their acid management regimen or wish to discuss upgrading to a prescription-strength acid reducer.
No. Aluminum hydroxide/magnesium hydroxide is not a controlled substance under the DEA Controlled Substances Act. It is an over-the-counter (OTC) medication available without a prescription at any pharmacy, grocery store, or online retailer. There are no purchase quantity limits, no ID requirements, and no special tracking for this medication.
While a prescription is not required, a healthcare provider can write a prescription for this medication if needed — for example, for FSA/HSA documentation, to track its use in a patient's medical record for a clinical indication, or if a patient is using it as part of a supervised treatment regimen for peptic ulcer disease or gastritis.
Most people tolerate this antacid well when used as directed. Common side effects include:
Serious side effects (contact a doctor immediately):
Know what you need? Skip the search.
Calcium Carbonate (Tums, Rolaids)
Widely available OTC antacid using calcium rather than aluminum/magnesium. Fast-acting, available as chewable tablets. Good for occasional heartburn; also provides calcium supplementation. May cause kidney stones with excessive use.
Famotidine (Pepcid AC)
H2 blocker that reduces acid production rather than neutralizing existing acid. Slower onset (30-60 min) but longer duration (8-12 hours). Better choice for frequent or nighttime heartburn. Available OTC and prescription.
Omeprazole (Prilosec OTC)
Proton pump inhibitor (PPI) providing 24-hour acid suppression. Best for GERD or heartburn 2+ times/week. Takes 1-4 days to reach full effect — not for immediate relief. Available OTC for 14-day treatment courses.
Sodium Bicarbonate (Alka-Seltzer)
Extremely fast-acting antacid for occasional heartburn. Avoid with sodium-restricted diets, hypertension, heart failure, or kidney disease. Causes gas/belching. Not for regular use.
Prefer Aluminum Hydroxide/Magnesium Hydroxide? We can find it.
Fluoroquinolone antibiotics (ciprofloxacin, levofloxacin)
majorAntacid chelates fluoroquinolone molecules, reducing antibiotic absorption by up to 90%. Separate by at least 2 hours (preferably 6 hours) to maintain antibiotic effectiveness.
Tetracycline antibiotics (doxycycline, minocycline)
majorChelation by aluminum and magnesium ions significantly reduces tetracycline absorption. Separate doses by at least 2 hours.
Levothyroxine (Synthroid)
majorAntacid reduces thyroid hormone absorption. Separate levothyroxine from antacids by at least 4 hours. Thyroid medication should be taken on an empty stomach 30-60 minutes before food.
Iron supplements (ferrous sulfate)
moderateRaised gastric pH reduces iron absorption. Iron requires acidic environment for optimal absorption. Separate iron supplements from antacids by at least 2 hours.
Azole antifungals (ketoconazole, itraconazole)
moderateAzole antifungals require acidic stomach pH for absorption. Antacids that raise pH can significantly reduce antifungal absorption and efficacy. Discuss timing with pharmacist.
Aspirin
minorAntacids may increase urinary elimination of aspirin, reducing its effectiveness. Of greater clinical concern at anti-inflammatory doses than at low cardiac-protective doses.
Aluminum hydroxide/magnesium hydroxide is a safe, effective, and widely available OTC antacid for occasional heartburn and acid indigestion. The combination formulation provides faster onset from magnesium hydroxide and longer duration from aluminum hydroxide, while balancing the constipating and laxative effects of each ingredient. At $6-15 per bottle, it is one of the most affordable heartburn treatments available.
Key things to remember: do not use for more than 2 weeks without physician guidance, separate all other oral medications by at least 2 hours, exercise caution if you have kidney disease, and consider switching to an H2 blocker or PPI if you find yourself reaching for this antacid more than 2-3 times per week.
If you're having trouble finding the right formulation at a pharmacy near you, medfinder calls pharmacies on your behalf to locate your medication and texts you the results — so you can spend less time on hold and more time feeling better.
Medfinder Editorial Standards
Our medication guides are researched and written to help patients make informed decisions. All content is reviewed for accuracy and updated regularly. Learn more about our standards
Real-time availability
Medfinder is actively checking pharmacy inventory for Aluminum Hydroxide/Magnesium Hydroxide. We don't publish a number until we have enough verified pharmacy checks to be accurate — start a search and our team confirms current availability near you, usually within 24 hours.
ChatGPT
Claude
Gemini