Aluminum Hydroxide/Magnesium Hydroxide Shortage: What Providers and Prescribers Need to Know in 2026

While aluminum hydroxide/magnesium hydroxide antacids are OTC products not typically on providers' radar for shortage management, several recent market changes have created confusion for patients — and increasingly, questions directed at clinical staff. This article provides a current clinical overview of the aluminum hydroxide/magnesium hydroxide landscape in 2026, covering market changes, clinical implications, and how to counsel patients who are having trouble finding their usual antacid.

Current Shortage Status: FDA Database Review

As of 2026, aluminum hydroxide/magnesium hydroxide is not listed in the FDA Drug Shortage Database. The OTC antacid market is served by multiple manufacturers producing both branded and generic versions, providing the supply redundancy that helps insulate this drug class from the shortages that affect more complex prescription medications.

However, two market events have disrupted patient access to familiar products:

• Maalox brand discontinuation: The U.S. brand-name Maalox has been removed from the market. Patients previously using Maalox (aluminum hydroxide/magnesium hydroxide/simethicone) are now relying on generic equivalents or Mylanta.
• Mylanta reformulation and relaunches: Mylanta was absent from U.S. shelves for several years following a brand ownership change, then relaunched under new ownership. Current Mylanta Maximum Strength (400mg aluminum hydroxide + 400mg magnesium hydroxide + 40mg simethicone per 5mL) is now available but not universally stocked.

Clinical Pharmacology Review

The aluminum hydroxide/magnesium hydroxide combination neutralizes gastric acid through direct acid-base chemistry. Aluminum hydroxide reacts with HCl to form aluminum chloride and water; magnesium hydroxide reacts to form magnesium chloride and water. This rapid neutralization raises gastric pH and provides symptom relief within minutes.

The combination formulation is designed to balance GI side effects: aluminum hydroxide causes constipation, while magnesium hydroxide has a laxative effect. In combination, these effects largely offset each other, resulting in a more tolerable GI profile than either agent used alone.

Formulary and Inpatient Considerations

For hospital and long-term care formularies, aluminum hydroxide/magnesium hydroxide is typically stocked as a unit-dose oral suspension. Hospital pharmacy buyers should be aware that specific vendors may have supply fluctuations in certain formulation strengths. If a preferred vendor is experiencing delays, consider:

• Switching to an equivalent generic from an alternate manufacturer (verify bioequivalence and mg/mL confirmation)
• Substituting with calcium carbonate suspension for appropriate patients (note different dosing and CI for hypercalcemia risk)
• Transitioning appropriate patients to famotidine or a PPI if ongoing acid suppression is clinically indicated

Drug Interaction Considerations for Providers

Aluminum hydroxide/magnesium hydroxide has 445 documented drug interactions. Providers switching patients between antacid formulations should note the mechanism underlying most of these interactions: the alkalinization of gastric pH and the chelation of drugs by aluminum and magnesium ions.

Key interaction categories to review when counseling patients:

• Fluoroquinolone and tetracycline antibiotics: Antacids substantially reduce absorption. Advise 2-hour separation.
• Levothyroxine: Antacids reduce thyroid hormone absorption. Advise 4-hour separation.
• Iron supplements: Antacids reduce iron absorption. Advise 2-hour separation.
• Antiretrovirals, antifungals: Complex interactions with pH-dependent absorption; review each agent individually.

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Special Populations: Renal Impairment

Providers should exercise particular caution in patients with renal impairment. Magnesium is renally cleared, and accumulation can lead to hypermagnesemia with symptoms including confusion, muscle weakness, respiratory depression, and cardiac conduction abnormalities. Aluminum accumulation with prolonged use in renal failure can cause osteomalacia and dialysis encephalopathy. In patients with significant CKD or ESRD, alternative antacids should be considered. If aluminum hydroxide is specifically needed for phosphate binding in CKD patients, this is a distinct clinical use that should be managed by nephrology.

How medfinder Supports Your Patients

When patients call your office or show up at a visit reporting they can't find their antacid, having a resource to point them to makes a difference. medfinder for providers is a service that calls pharmacies on patients' behalf to locate their medication and text them results. You can read more about how this works in our provider guide to helping patients find antacids.