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Gas-X Ultra Strength Side Effects

Generic name: simethicone

Medically reviewed by Last updated on Feb 2, 2024.

Note: This document contains side effect information about simethicone. Some dosage forms listed on this page may not apply to the brand name Gas-X Ultra Strength.

Applies to simethicone: oral capsule liquid filled, oral solution, oral suspension, oral tablet, oral tablet chewable.

There have not been any common or important side effects reported with this medicine. However, if you notice any side effects, check with your doctor.

For Healthcare Professionals

Applies to simethicone: compounding liquid, compounding powder, oral capsule, oral disintegrating strip, oral liquid, oral suspension, oral tablet, oral tablet chewable.


Uncommon (0.1% to 1%): Constipation, nausea

Rare (0.01% to 0.1%): Tongue edema[Ref]


Rare (0.01% to 0.1%): Face edema, hypersensitivity reactions[Ref]


Rare (0.01% to 0.1%): Respiratory difficulty[Ref]


Rare (0.01% to 0.1%): Pruritus, rash[Ref]

More about Gas-X Ultra Strength (simethicone)

Patient resources

Other brands

Mylicon, Maalox Anti-Gas, Phazyme, Alka-Seltzer Anti-Gas, ... +14 more

Professional resources

Other formulations

Related treatment guides


1. (2001) "Product Information. Mylicon (simethicone)." Johnson and Johnson Medical Inc

2. (2003) "Product Information. Maalox Anti-Gas Extra Strength (simethicone)." Novartis Consumer Health

3. Cerner Multum, Inc. "UK Summary of Product Characteristics."

4. Cerner Multum, Inc. "Australian Product Information."

Further information

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.

Some side effects may not be reported. You may report them to the FDA.