aluminum hydroxide/magnesium hydroxide/simethicone

Medically Reviewed on 7/20/2022

Generic Name: aluminum hydroxide/magnesium hydroxide/simethicone

Brand Names: Mylanta, Mygel, DiGel, Gelusil, Rulox

Drug Class: Antacids, Combos

What is aluminum hydroxide/magnesium hydroxide/simethicone, and what is it used for?

Aluminum hydroxide/magnesium hydroxide/simethicone is a combination medication used to relieve symptoms of acid indigestion, heartburn, sour stomach, upset stomach, and bloating.

The drug formulations contain varying compositions of the three components and are available over the counter (OTC). Aluminum hydroxide and magnesium hydroxide are antacids while simethicone is an antiflatulent drug that reduces abdominal gas and bloating.

Both aluminum hydroxide and magnesium hydroxide neutralize the hydrochloric acid in the stomach acid, protecting the gastrointestinal (GI) lining from its corrosive effects. Both bind to hydrochloric acid and form salts and water that are eliminated in the stools. Magnesium hydroxide is a rapid-acting antacid in the stomach while aluminum hydroxide sustains the effects.

Magnesium hydroxide also draws water into the colon, acting as a laxative and promoting bowel movement. Aluminum hydroxide is an astringent that can cause constipation and this effect is balanced by magnesium hydroxide’s laxative properties. Aluminum hydroxide also prevents the absorption of dietary phosphate and reduces phosphate levels in blood. However, neither antacid has an effect on the stomach’s acid production.

Simethicone is a silicone compound that is not systemically absorbed and is excreted in the stools. Simethicone is a surfactant that changes the surface tension of gas bubbles causing them to collapse, which enables easier passage of gas and prevents the formation of gas pockets in the GI tract and the resultant abdominal bloating. Simethicone, however, does not prevent the formation of gas in the GI tract or treat conditions that increase gas production.


  • Do not use aluminum hydroxide/magnesium hydroxide/simethicone if you are hypersensitive to any of the components in the formulation.
  • Do not take aluminum hydroxide/magnesium hydroxide/simethicone if you have kidney disease.
  • Prolonged use may cause low blood phosphate levels (hypophosphatemia), which may lead to loss of appetite (anorexia), weakness and softening of bones (osteomalacia). Use with caution.
  • Do not use the combo drug to treat hyperphosphatemia.
  • Aluminum hydroxide/magnesium hydroxide/simethicone can cause high magnesium levels (hypermagnesemia) or aluminum intoxication, especially in patients with renal insufficiency, and may lead to osteomalacia and dialysis encephalopathy, an aluminum-related brain damage.
  • May increase or decrease the rate of absorption of other oral drugs administered concurrently.
  • Some formulations may contain propylene glycol which is toxic in large amounts.
  • Some formulations may contain sodium and may not be suitable for people on restricted sodium diets.
  • Some formulations may contain phenylalanine and should not be used in patients with phenylketonuria, an inherited condition with inability to break down phenylalanine.

What are the side effects of aluminum hydroxide/magnesium hydroxide/simethicone?

Common side effects of aluminum hydroxide/magnesium hydroxide/simethicone include:

Aluminum hydroxide

  • Nausea
  • Vomiting
  • Chalky taste
  • Stomach cramps
  • Constipation
  • Fecal impaction
  • Hemorrhoids
  • Rebound hyperacidity
  • Aluminum intoxication
  • Softening of bones (osteomalacia)
  • Milk-alkali syndrome, a condition with
    • High calcium in blood (hypercalcemia)
    • High alkalinity of tissues (metabolic alkalosis)
    • Kidney injury
  • Low phosphate levels in blood (hypophosphatemia)

Magnesium hydroxide


Call your doctor immediately if you experience any of the following symptoms or serious side effects while using this drug:

This is not a complete list of all side effects or adverse reactions that may occur from the use of this drug. Call your doctor for medical advice about serious side effects or adverse reactions. You may also report side effects or health problems to the FDA at 1-800-FDA-1088.


Pancreatitis is inflammation of an organ in the abdomen called the pancreas. See Answer

What are the dosages of aluminum hydroxide/magnesium hydroxide/simethicone?


  • (200 mg/200 mg/20 mg)/5 mL
  • (400 mg/400 mg/40 mg)/5 mL


  • (225 mg/200 mg/25 mg)/5 mL


Dyspepsia, Abdominal Bloating

  • 10-20 mL orally every 4-6 hours taken 1 hour before or 3 hours after meals, OR
  • Chew 2-4 tablets every 4-6 hours; not to exceed 12 tablets/24 hours


  • Safety and efficacy not established


  • Overdose of aluminum hydroxide/magnesium hydroxide/simethicone combo is unlikely to cause serious side effects. Overdose may cause constipation or diarrhea and the symptoms should resolve with discontinuation of the drug.
  • Chronic use may cause accumulation of aluminum resulting in aluminum toxicity and increased blood levels of magnesium.

What drugs interact with aluminum hydroxide/magnesium hydroxide/simethicone?

Inform your doctor of all medications you are currently taking, who can advise you on any possible drug interactions. Never begin taking, suddenly discontinue, or change the dosage of any medication without your doctor’s recommendation.

  • Severe interactions of aluminum hydroxide/magnesium hydroxide/simethicone include:
  • Aluminum hydroxide/magnesium hydroxide/simethicone has serious interactions with at least 30 different drugs.
  • Aluminum hydroxide/magnesium hydroxide/simethicone has moderate interactions with at least 128 different drugs.
  • Aluminum hydroxide/magnesium hydroxide/simethicone has mild interactions with at least 60 different drugs.

The drug interactions listed above are not all of the possible interactions or adverse effects. For more information on drug interactions, visit the RxList Drug Interaction Checker.

It is important to always tell your doctor, pharmacist, or health care provider of all prescription and over-the-counter medications you use, as well as the dosage for each, and keep a list of the information. Check with your doctor or health care provider if you have any questions about the medication.

Pregnancy and breastfeeding

  • Use aluminum hydroxide/magnesium hydroxide/simethicone during pregnancy only if maternal benefits outweigh potential risks to the fetus.
  • It is not known if aluminum hydroxide/magnesium hydroxide/simethicone is present in breast milk. Use with caution in nursing mothers.

What else should I know about aluminum hydroxide/magnesium hydroxide/simethicone?

  • Take aluminum hydroxide/magnesium hydroxide/simethicone exactly as per label instructions.
  • Check with your doctor before taking OTC aluminum hydroxide/magnesium hydroxide/simethicone if you are on a sodium or magnesium-restricted diet.
  • Do not self-medicate for longer than 14 days. If symptoms don’t resolve, discontinue the drug and consult with your physician. 
  • Store safely out of reach of children.
  • In case of overdose, seek medical help or contact Poison Control.


Aluminum hydroxide/magnesium hydroxide/simethicone is a combination medication used to relieve symptoms of acid indigestion, heartburn, sour stomach, upset stomach, and bloating. Side effects include nausea, vomiting, chalky taste, stomach cramps, constipation Abdominal pain, diarrhea, rectal bleeding, electrolyte imbalance, high magnesium in the blood (hypermagnesemia), and others. Do not take long term. Consult your doctor before taking if pregnant or breastfeeding.

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Medically Reviewed on 7/20/2022