A combination antacid containing aluminum hydroxide and magnesium hydroxide, used for the symptomatic relief of heartburn, acid indigestion, sour stomach, and peptic ulcer pain. The combination balances the constipating effect of aluminum with the laxative effect of magnesium.
Balanced GI side effect profile (compared to single-agent antacids)
What to watch for
Diarrhea (magnesium component)
Constipation (aluminum component)
Hypermagnesemia in renal impairment
Severe renal impairment (risk of magnesium and aluminum accumulation)1,2
Hypophosphatemia
The bottom line
Evidence rating strong. Most-documented uses: rapid relief of heartburn and acid indigestion, sour stomach relief, symptomatic relief of peptic ulcer pain. 10 sources indexed (1983–2025), with 3 interaction records on file.
The science
How it works, mechanistically.
Core mechanism
Aluminum hydroxide and magnesium hydroxide directly neutralize gastric hydrochloric acid in the stomach, raising intragastric pH. Aluminum hydroxide also inhibits pepsin activity at pH above 4.0 and binds bile acids. The combination provides effective acid neutralization while minimizing bowel habit changes.1,2
Class
Antacid
Dosing
Dosing & protocol.
Common range
10–20 mL or 1–2 tablets as needed, up to 4 times daily (as prescribed by your physician)
Recommended form
Oral suspension or chewable tablet
Take 1–3 hours after meals and at bedtime for ulcer treatment; separate from other medications by at least 2 hours to avoid absorption interference9
Depletions
What it depletes.
Nutrients this medication can lower over time, and what to replace.
Phosphorus
Significant
Aluminum-containing antacids bind phosphate in the gut and can lower phosphorus status during repeated use.
Monitor Serum phosphorusOnset Usually with repeated or chronic use
Iron
Mild
Antacids reduce iron absorption by raising gastric pH and reducing non-heme iron solubility.
Aluminum and magnesium in antacids form insoluble chelate complexes with ciprofloxacin in the gut, dramatically reducing antibiotic absorption. Studies have shown bioavailability reductions of 50 to 90 percent when taken together, which can drop ciprofloxacin levels below the threshold needed to clear infection. This is one of the most clinically significant absorption interactions for fluoroquinolones.
Recommendation: Take ciprofloxacin at least 2 hours before or 6 hours after any aluminum or magnesium hydroxide antacid. Do not co-administer in the same dose.
Aluminum and magnesium in antacids form insoluble chelate complexes with levofloxacin in the gut, reducing antibiotic absorption by 50 percent or more. This is one of the most clinically significant absorption interactions for levofloxacin.
Recommendation: Take levofloxacin at least 2 hours before or 2 hours after any aluminum or magnesium hydroxide antacid. Do not co-administer in the same dose.
Aluminum and magnesium in antacids chelate doxycycline in the gut, dramatically reducing its absorption. Bioavailability reductions of 50 percent or more are typical with concurrent dosing. Subtherapeutic doxycycline can cause treatment failure for infections such as Lyme disease, rickettsial illness, or community-acquired pneumonia.
Recommendation: Take doxycycline at least 2 hours before or 6 hours after any aluminum or magnesium hydroxide antacid. Do not co-administer.
Nate-Anong B, Khorana J, Chantakhow S et al.. Sennosides vs magnesium hydroxide vs polyethylene glycol as a treatment for constipation in anorectal malformation: a randomized crossover trial. Pediatric surgery international. 2025
Hürlimann S, Michel K, Inauen W et al.. Effect of Rennie Liquid versus Maalox Liquid on intragastric pH in a double-blind, randomized, placebo-controlled, triple cross-over study in healthy volunteers. The American journal of gastroenterology. 1996
Hunter JO, Walker RJ, Crowe J et al.. Double-blind randomized multicenter study comparing Maalox TC tablets and ranitidine in healing of duodenal ulcers. Digestive diseases and sciences. 1991
Becker LC, Boyer I, Bergfeld WF et al.. Safety Assessment of Alumina and Aluminum Hydroxide as Used in Cosmetics. International journal of toxicology. 2016
This page is educational. Do not start, stop, or change a supplement or medication based on it without checking with a qualified healthcare professional.
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