Simethicone is a poly (dimethylsiloxane) which is a polymer of 200-350 units of dimethylsiloxane, along with added silica gel. It is used as an antiflatulent, surfactant, and ointment base. Simethicone is an orally administered anti-foaming agent used to reduce bloating, discomfort or pain caused by excessive gas — mainly swallowed air, with small amounts of hydrogen and methane in the stomach or intestines.