What Is Bis-Peg/Ppg-21/7 Dimethicone?
Bis-Peg/Ppg-21/7 Dimethicone is a silicone-based ingredient created by attaching a mix of 21 ethylene oxide units and 7 propylene oxide units to each end of a dimethicone chain. These added “peg” and “ppg” blocks make the normally water-repelling silicone partly water-loving, so it can blend into both oil and water phases of a cosmetic formula.
The backbone of the material, dimethicone, has been used in beauty products since the 1950s for its silky slip and protective feel. Chemists later discovered that linking dimethicone with polyethers produced a lighter texture and improved spreadability. As a result brands adopted Bis-Peg/Ppg-21/7 Dimethicone in the 1990s when consumers began asking for products that felt weightless yet still protective.
Manufacturing starts with medical-grade silica that is transformed into dimethicone fluid. Under controlled heat and pressure, each end of this fluid is reacted with specific amounts of ethylene oxide and propylene oxide. The random addition of those 28 small units gives the “21/7” ratio, creating a uniform but flexible polymer. The finished ingredient is purified and quality-checked before shipment to cosmetic labs.
You will see Bis-Peg/Ppg-21/7 Dimethicone in rinse-off and leave-on hair products such as shampoos, conditioners and smoothing serums. It is also common in facial moisturizers, primers, sunscreens, sheet masks, gentle cleansers and light body lotions where formulators want the conditioning touch of silicone without a heavy feel.
Bis-Peg/Ppg-21/7 Dimethicone’s Cosmetic Benefits/Uses
This versatile polymer earns its place on an ingredient list because it can perform several helpful jobs at once.
- Hair conditioning: Forms a thin, flexible film over strands that smooths cuticles, reduces frizz and boosts shine while rinsing out easily so hair does not feel coated
- Skin conditioning: Leaves a soft, non-greasy finish on the skin surface, helping it feel silky and appear smoother
- Emollient: Fills in tiny gaps on the skin or hair surface, locking in moisture and lending a cushiony touch
- Cleansing: Lowers surface tension to help water lift away dirt and makeup more effectively without stripping natural oils
- Emulsifying: Helps keep oil and water mixed, stabilizing lotions, creams, and milky cleansers so they stay uniform over their shelf life
Who Can Use Bis-Peg/Ppg-21/7 Dimethicone
Most skin types can comfortably use this ingredient. Its lightweight silky texture works well for oily and combination skin because it does not feel greasy and helps reduce transepidermal water loss. Dry and mature skin benefit from the soft protective film it forms, which holds moisture in. Even sensitive skin generally tolerates it since the molecule is too large to penetrate deeply, though anyone with a known silicone sensitivity should avoid it.
Because Bis-Peg/Ppg-21/7 Dimethicone is produced from mineral silica and petrochemical feedstocks, not animals, it is suitable for vegans and vegetarians. No animal derivatives or animal testing are required for its manufacture by reputable suppliers.
The ingredient is considered low risk for women who are pregnant or breastfeeding. Its high molecular weight keeps it on the skin’s surface rather than entering the bloodstream. That said this is not medical advice and pregnant or nursing individuals should clear any new skincare product with their doctor just to be safe.
It does not increase photosensitivity, so wearing it during daytime does not heighten sunburn risk. Standard sunscreen use is still advised for overall protection. The ingredient is water dispersible yet rinses clean, making it compatible with almost any daily routine for skin or hair.
Potential Side Effects/Adverse Reactions
Reactions to topically applied Bis-Peg/Ppg-21/7 Dimethicone vary by individual. The points below list potential side effects that are possible but not common. When the ingredient is used at normal cosmetic levels most people experience no problems.
- Mild redness or irritation in those with an existing silicone intolerance
- Allergic contact dermatitis which is extremely rare but can occur in sensitized individuals
- Temporary clogged pores on highly acne prone skin if heavy layers of multiple occlusives are combined
- Product buildup on hair leading to limpness or dullness if cleansing is insufficient
If any discomfort or adverse change in skin or hair appears stop using the product and seek guidance from a healthcare professional or dermatologist.
Comedogenic Rating
Rating: 1 / 5
Bis-Peg/Ppg-21/7 Dimethicone sits on the surface of skin, is partly water loving and rinses away more easily than heavier silicones, so it is unlikely to clog pores. A small chance of congestion can appear if it is layered with many other occlusive ingredients, which is why it is given a 1 rather than a perfect 0.
Most people who are prone to acne can use it without seeing more breakouts.
Keep in mind that the overall formula matters. A lightweight gel that contains this silicone will feel very different from a thick cream loaded with waxes and oils.
Summary
Bis-Peg/Ppg-21/7 Dimethicone conditions hair, softens skin, works as an emollient, helps cleanse and stabilises oil-in-water mixes. It does this by forming a thin flexible film that smooths surfaces while its peg-ppg blocks let it mix with both water and oil so it can spread out evenly and rinse off clean.
The ingredient is a quiet workhorse rather than a headline grabber. It turns up in many shampoos, lightweight creams and sunscreens because formulators like its silky slip and easy rinse yet most shoppers never notice it by name.
Safety studies and decades of use show a low risk of irritation or acne for most users. Still, skin is personal so it is wise to patch test any new product that contains this or any other unfamiliar ingredient.