Simethicone is an oral anti-foaming agent used to reduce bloating, discomfort and pain caused by excess gas in the stomach or intestinal tract. It is a mixture of polydimethylsiloxane and silica gel. Simethicone is an anti-foaming agent that decreases the surface tension of gas bubbles, causing them to combine into larger bubbles in the stomach that can be passed more easily by burping. Simethicone does not reduce the quantity of gas in the digestive tract, it only increases the rate at which it exits the body, but does not prevent gas formation in the intestine. However, simethicone can relieve pain caused by gas in the intestines by decreasing foaming which then allows for passing of flatus. Simethicone is not absorbed by the body into the bloodstream, and is therefore considered relatively safe, with sources reporting the worst side effects as bloating, constipation, diarrhea, gas and heartburn. Simethicone solutions of differing concentration also have industrial applications for reducing foaming in certain chemical processes.