What Is Bis(Ppg-7 Undeceneth-21) Dimethicone?
Bis(Ppg-7 Undeceneth-21) Dimethicone is a specialty silicone made by bonding a dimethicone backbone to chains of polypropylene glycol and polyethylene glycol. The result is a silky fluid that marries the slip of traditional silicones with the water-friendly character of glycols. Manufacturers start with basic silicone oil, react it with epoxy-capped PPG and PEG segments, then cap the ends with an undecenyl group to improve spreadability. This tailored approach first appeared in the late 1990s when formulators wanted silicones that could mix easily with water-based lotions without a heavy feel.
Its balanced structure lets it dissolve in both oils and water so it shows up in a wide range of leave-on and rinse-off products. You will see it in lightweight moisturizers, hydrating serums, anti-aging creams, creamy face masks, gentle facial cleansers, two-phase makeup removers, conditioning shampoos, smoothing hair masks and frizz-taming styling creams.
Bis(Ppg-7 Undeceneth-21) Dimethicone’s Cosmetic Benefits/Uses
This multi-tasker brings several helpful roles to a formula
- Hair conditioning: Forms a thin flexible film on strands that boosts softness, eases detangling and adds slip without a greasy feel
- Skin conditioning: Leaves a smooth protective layer on the skin surface that reduces moisture loss and gives a silky after-feel
- Emollient: Fills in tiny surface gaps so skin feels velvety and hair looks smoother and shinier
- Cleansing: Helps lift dirt and makeup while preventing the tight dry sensation some surfactants cause
- Emulsifying: Bridges water and oil phases so creams stay stable, light and uniform during shelf life
Who Can Use Bis(Ppg-7 Undeceneth-21) Dimethicone
This silicone-glycol hybrid sits well on most skin types. Dry and mature skin benefit from the light occlusive layer that slows water loss while oily and combination skin appreciate its non-greasy slip that does not feel heavy. Sensitive skin generally tolerates it because it is inert and fragrance-free, though anyone extremely reactive to silicones might prefer caution. Acne-prone users find it less likely to clog pores than heavier oils but very congested skin could still notice build-up if formulas are not rinsed thoroughly.
The ingredient is fully synthetic with no animal-derived substrates so it is suitable for vegans and vegetarians. Manufacturers typically source the PPG and PEG chains from petrochemical or plant-based feedstocks that do not involve animal by-products.
No evidence suggests a risk for pregnant or breastfeeding women when the ingredient is used topically because its large molecular size limits penetration through the skin. This is not medical advice and anyone who is pregnant or nursing should show the complete product to a qualified healthcare provider before regular use just to be safe.
Bis(Ppg-7 Undeceneth-21) Dimethicone is not known to cause photosensitivity and does not interfere with sunscreens. It can be used morning or night without extra sun precautions beyond a normal daily SPF.
Potential Side Effects/Adverse Reactions
Responses to topical Bis(Ppg-7 Undeceneth-21) Dimethicone differ slightly from person to person. The points below list potential issues but they are uncommon when the ingredient is included at normal cosmetic levels and manufactured correctly.
- Mild transient redness or itching in individuals who are sensitive to silicones
- Rare allergic contact dermatitis triggered by the PEG or PPG segments
- Follicular occlusion leading to whiteheads in very acne-prone users if layered with multiple silicone-rich products
- Watery eyes or temporary stinging if a formula containing it accidentally gets into the eyes
- Slippery residue on shower floors when used in rinse-off hair products which could increase fall risk
If any of these reactions occur stop using the product and consult a healthcare professional for guidance.
Comedogenic Rating
Rating: 1/5. Bis(Ppg-7 Undeceneth-21) Dimethicone sits mostly on the surface, forms a breathable film and has a large molecular size that keeps it from sinking into pores, so it is far less likely to trap sebum compared with heavier oils or waxes. Its partial water solubility also allows easier rinse-off than traditional dimethicone. This makes it generally suitable for acne-prone or breakout-prone skin. Extremely oily skin, or skin already layered with several silicone-rich products, might still notice congestion if cleansing is inadequate, but that remains the exception rather than the rule.
Summary
Bis(Ppg-7 Undeceneth-21) Dimethicone conditions hair, smooths skin, softens textures, aids cleansing and stabilizes emulsions by combining a silky silicone backbone with water-friendly glycol chains. That dual nature lets it spread easily, lock in moisture and wash away without heavy buildup. The ingredient shows up in a fair number of modern lightweight lotions and shampoos, though it is not yet a household name like plain dimethicone.
Current research and decades of safe use point to a low irritation profile, minimal pore-clogging risk and no known systemic concerns. As with any new cosmetic, do a small patch test first to be extra safe, especially if you have highly reactive or acne-prone skin.