Simethicone is a mixture of two components: dimethicone (a type of silicone oil) and silicon dioxide (silica gel). The NHS describes it as “activated dimethicone,” meaning it’s essentially the same silicone polymer used in skin creams and hair products, but blended with silica to give it anti-foaming properties. That combination is what makes it work against gas and bloating.
The Two Core Ingredients
The silicone oil in simethicone is polydimethylsiloxane, a long chain of repeating silicon and oxygen units with small methyl groups attached. This is the same family of silicone found in countless consumer products, from cosmetic moisturizers to lubricants. On its own, this silicone oil is called dimethicone. It’s inert, meaning your body doesn’t absorb or break it down.
What transforms dimethicone into simethicone is the addition of silicon dioxide, a fine powder better known as silica gel. Silica disperses throughout the silicone oil and dramatically boosts its ability to break down foam. According to U.S. Pharmacopeia standards, the polydimethylsiloxane content in simethicone products must fall between 85% and 110% of the labeled amount, ensuring consistency across brands.
How These Ingredients Work Together
Simethicone acts as a defoaming agent. Gas in your stomach and intestines doesn’t just float around freely. It gets trapped in tiny bubbles surrounded by mucus, forming a frothy layer that can cause pressure, bloating, and discomfort. Simethicone lowers the surface tension of those mucus-coated bubbles, causing them to merge into larger bubbles that your body can expel more easily through burping or passing gas.
The silicone oil provides the surface-tension-lowering effect, while the silica gel makes that effect stronger and more consistent. Neither ingredient gets absorbed into your bloodstream. Simethicone passes through your digestive tract completely unchanged, which is why it has virtually no systemic side effects and is considered safe even for infants.
What’s in the Tablet or Liquid You Actually Take
The simethicone itself is only one part of what’s in a chewable tablet, capsule, or liquid suspension. The rest consists of inactive ingredients that give the product its shape, texture, and flavor. A typical chewable tablet contains microcrystalline cellulose (a plant-based filler), maltodextrin and dextrose (mild sweeteners derived from starch), sorbitol (a sugar alcohol), sucrose, stearic acid (a binding agent), silicon dioxide, and peppermint flavoring.
Liquid drops, often used for infants, use a different set of carriers to keep the simethicone evenly suspended. The active ingredient is identical across all forms. The only real difference between a chewable tablet, a soft gel capsule, and liquid drops is how the simethicone is delivered and how quickly it disperses in your stomach.
Simethicone vs. Dimethicone
Because simethicone is built from dimethicone, the two names sometimes cause confusion. The distinction is straightforward: dimethicone is the pure silicone oil, and simethicone is that same oil activated with silica gel. Dimethicone on its own is widely used in skincare as a moisturizing and smoothing agent. Adding silica turns it into a much more effective foam-breaker, which is why the activated form is the one used in gas relief products.
You may also see the spelling “simeticone” and “dimeticone” on products sold in the UK and Europe. These are the same compounds, just using the international naming convention rather than the American one.
Typical Dosing
Adults and teenagers generally take 40 to 125 mg of simethicone up to four times a day, after meals and at bedtime. The maximum in a 24-hour period is 500 mg regardless of the form you’re using. Because simethicone isn’t absorbed, going slightly over a dose isn’t dangerous in the way it would be with most medications, but sticking to the labeled amount is still the best practice. Doses for children vary by age and weight, so pediatric use should follow a doctor’s guidance.