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Also known under the trade names Phazyme and Mylicon.

Chemical formula:
(CH3)3SiO[Si(CH3)2O]nSi(CH3)3 {n: 200 < n < 350}
The chemical chain [-Si(CH3)2O-]n is called poly(dimethylsiloxane), and it is both literally and figuratively the backbone of the silicone industry. All silicones are formed around a chain of Si-O atoms, frequently with organic groups attached by an Si-C bond. PDMS is the most common example, and looks like this:

     H      H      H
     |      |      |
   H-C-H  H-C-H  H-C-H
     |      |      |
... -Si--O--Si--O--Si--O- ...
     |      |      |
   H-C-H  H-C-H  H-C-H
     |      |      |
     H      H      H

Simethicone is an over the counter drug (see note below) used as anti-gas medicine. It works by breaking down the surface tension which allows bubbles and foam to form, making it easier to pass the gas out of your system (it does not actually prevent gas, it just eases discomfort caused by gas). It is available in capsules or tablets (60-125mg), chewable tablets (40-125mg), or as a liquid suspension (40-95mg). Dosages for children should be determined by a doctor.

Medicine containing Simethicone should be stored in a tightly closed container, out of the light, and away from heat and moisture (that is, do not store in the bathroom). Simethicone is an active ingredient in a number of medicines, including:

  • Maalox
  • Flatulex
  • Gas-X
  • Genasyme
  • Mylanta
  • Phazyme
  • My Baby Gas Relief Drops
  • Mylicon Drops
  • Phazyme
  • Ovol (in Canada)

Simethicone is very safe, since it is not actually absorbed by the body. Missed dosages are not a significant problem, and overdoses are very unlikely to cause any serious harm. There are no known interactions with other drugs, food, or vitamins (although some people are allergic) and it is safe for pregnant and nursing mothers. It can be taken for long periods of time with no additional risks. Side effects, though rare, include bloating, constipation, diarrhea, gas, and heartburn.

My personal experience with Simethicone (in Mylanta) suggests that for best results, take the recommended dosage once about ten minutes before eating foods likely to cause gas problems.

Special thanks to vuo for pointing me to the information I needed on PDMS, and also for letting me know that Simethicone is not technically a drug since it is chemically inert and not absorbed by the body. Its physical properties as a surfactant (as opposed to chemical properties), however, are useful for controlling gas problems.


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