Simethicone is an anti-foaming agent that is taken orally to help reduce the buildup of intestinal and stomach gases that cause bloating and discomfort.

OTC/Lifestyle Pearl of the Day: Simethicone (Gas-X)

Indication: Gas-X works with your body to help relieve gas.

Insight:

Simethicone is the active ingredient in Gas-X.
It’s an anti-foaming agent that is taken orally to help reduce the buildup of intestinal and stomach gases that cause bloating and discomfort.
Dose ranges from 125 mg to 250 mg and taken in 2 to 4 tablets per day.
Dosage forms: Gas-x comes in tablet, capsule, tablet-chewable, liquid, oral suspension, and strips of oral distinguishing format
Adverse effects include rash, itching, swelling, severe dizziness and trouble breathing.

Sources:

Gas-X Usage & Directions | Gas-X Gas Relief
gas-x side effects - Bing