Medically Reviewed on 10/20/2022

Brand Name: Phazyme, Mi-Acid, Gas Relief, Mytab Gas, Gas-X, Gas-X Extra Strength, Mylanta, Mygel, DiGel, Gelusil, Rulox

Generic Name: Aluminum Hydroxide/Magnesium Hydroxide/Simethicone

Drug Class: Antacids, Combos

What is simethicone, and how does it work (mechanism of action)?

Simethicone is an anti-gas (anti-flatulence) medication. It acts in the stomach and intestines to change the surface tension of gas bubbles, enabling their breakdown and the formation of larger bubbles. In this way, it is believed that gas can be eliminated more easily by belching or passing flatus. Simethicone was approved by the FDA in 1952.

Do I need a prescription for simethicone?


What are the uses for simethicone?

Simethicone relieves abdominal pain due to excessive gas in the digestive tract. It also is given to patients undergoing upper abdominal ultrasound imaging.

What are the side effects of simethicone?

Common side effects of simethicone may include:

Serious side effects of simethicone include:

  • rebound hyperacidity,
  • aluminum-intoxication,
  • low blood phosphates (hypophosphatemia),
  • chalky taste,
  • constipation (this could lead to hemorrhoids or bowel obstruction),
  • fecal impaction,
  • stomach cramps,
  • milk-alkali syndrome, and
  • softening of the bones.

What is the dosage for simethicone?

  • The recommended dose for relieving gas is 40-125 mg 4 times daily after meals and at bedtime.
  • The dosage can be mixed with water, infant formula, or other liquids for use in small children.


Super Tips to Boost Digestive Health: Bloating, Constipation, and More See Slideshow

Which drugs or supplements interact with simethicone?

  • Simethicone has severe interactions with the following drug:
  • Simethicone has serious interactions with the following drugs:
  • Aluminum Hydroxide/Magnesium Hydroxide/Simethicone has moderate interactions with at least 132 other drugs.
  • Aluminum Hydroxide/Magnesium Hydroxide/Simethicone has minor interactions with at least 59 other drugs.

This information does not contain all possible interactions or adverse effects. Visit the RxList Drug Interaction Checker for any drug interactions. Therefore, before using this product, tell your doctor or pharmacist about all the products you use. Keep a list of all your medications with you and share this information with your doctor and pharmacist. Check with your healthcare professional or doctor for additional medical advice, or if you have health questions or concerns.

Is simethicone safe to take if I'm pregnant or breastfeeding?

  • Safety during pregnancy has not been adequately evaluated. Simethicone is generally considered safe during pregnancy because it does not cross the placenta.
  • Simethicone is considered safe during lactation because it is not absorbed into the body and infants are often treated with simethicone.

What else should I know about simethicone?

What preparations of simethicone are available?
  • Liquid drops: 40 mg per 0.6 ml. Chewable tablets: 40, 80 and 125 mg. Capsules: 125 and 180 mg.
How should I keep simethicone stored?
  • Preparations should be stored at room temperature, 15 C - 30 C (59 F - 86 F).


Simethicone (Phazyme, Mi-Acid, Gas Relief, Mytab Gas, Gas-X, Gas-X Extra Strength, Gas-X Ultra Strength) is an antigas medication used to relieve abdominal pain caused by excessive gas. Review side effects, drug interactions, dosage, and pregnancy safety information prior to taking this medication.

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Medically Reviewed on 10/20/2022
FDA Prescribing Information.

Black R, Hill A. Over the counter medications in pregnancy. Am Fam Physician. 2003 Jun 15;67(12):2517-2524.