What Is Bis-C16-18 Alkyl Glyceryl Undecyl Dimethicone?
Bis-C16-18 Alkyl Glyceryl Undecyl Dimethicone is a specialty silicone that joins a dimethicone backbone with natural-style fatty chains derived from coconut or palm oil plus a small piece of glycerin and undecyl (11-carbon) alcohol. The result is a hybrid molecule that behaves like both a lightweight oil and a silky silicone. Chemists first began grafting fatty acids onto silicones in the late 1990s to improve how silicones spread on skin and to help water and oil mix more easily in lotions. This particular blend grew popular in the last decade because the mix of C16-C18 chains, glycerin and undecyl groups gives it extra affinity for skin while keeping formulas stable.
Manufacturing starts with medical-grade dimethicone. Through controlled reactions the chemist caps each end of the polymer with C16-C18 alkyl dimethylsilyl groups, then links in glycerin and undecyl segments. The finished ingredient is a clear fluid that disperses easily in both oils and some water-based systems.
Because it improves texture and stability, you will spot Bis-C16-18 Alkyl Glyceryl Undecyl Dimethicone in facial moisturizers, primers, anti-aging serums, BB and CC creams, masks, sun care, leave-on hair conditioners and even gentle cleansing balms.
Bis-C16-18 Alkyl Glyceryl Undecyl Dimethicone’s Cosmetic Benefits/Uses
In formulas this multitasker brings several helpful actions:
- Emulsion stabilising: Keeps oil and water phases from separating so creams stay smooth and uniform during shelf life and while you apply them
- Film forming: Lays down a soft breathable layer that helps lock in moisture, improves spreadability and boosts wear time for makeup and sunscreens
- Cleansing: Acts like a mild surfactant that can lift away dirt and makeup without stripping skin which is why it shows up in balm and oil cleansers
Who Can Use Bis-C16-18 Alkyl Glyceryl Undecyl Dimethicone
This silicone-fatty hybrid is generally suitable for all skin types, including dry, normal, combination and oily. Its light, non-greasy feel means it will not weigh down oily skin while the soft film it forms can help dry or sensitive skin hold on to moisture. People with very acne-prone skin may still want to watch how their skin responds because any occlusive layer, even a breathable one, can sometimes trap existing sebum and debris.
The ingredient itself is synthetic and does not rely on animal-derived materials so it is considered suitable for vegans and vegetarians. That said, always check the full product label because other ingredients in the same formula might not be vegan.
No specific warnings exist for pregnant or breastfeeding women. Current safety data show it does not penetrate deeply into skin or enter the bloodstream in meaningful amounts. Still, this is not medical advice and anyone who is pregnant or nursing should run new skincare products past a qualified doctor just to be safe.
Bis-C16-18 Alkyl Glyceryl Undecyl Dimethicone does not cause photosensitivity, meaning it will not make skin more likely to burn in the sun. Normal daily sun protection habits should still be followed.
Potential Side Effects/Adverse Reactions
How skin reacts to any cosmetic ingredient can differ from person to person. The points below list potential but uncommon side effects linked to topical use of Bis-C16-18 Alkyl Glyceryl Undecyl Dimethicone when it is formulated correctly most users will not encounter these problems.
- Mild irritation a small number of users may experience redness or itching, especially if their skin is already compromised
- Temporary stinging around eyes if the product migrates into the eye area before it has set
- Clogged pores very oily or acne-prone skin could see an increase in congestion if the rest of the routine is already heavy in occlusives
- Allergic contact dermatitis rare but possible for individuals with a silicone or fatty alcohol sensitivity
If any of these reactions occur stop using the product and seek advice from a medical professional.
Comedogenic Rating
Rating: 2 out of 5. Although the base dimethicone is classed as non-comedogenic, the attached C16-18 fatty chains add a light occlusive quality that can trap oil if layered heavily. Most users will not notice clogged pores, yet very oily or congestion-prone skin might.
Generally fine for people who break out easily but keep the rest of the routine light and watch how your skin responds.
Formula weight, concentration and what other occlusive agents sit alongside it matter more than the molecule itself so a gel-cream with a small dose will feel far less pore-coating than a rich balm packed with it.
Summary
Bis-C16-18 Alkyl Glyceryl Undecyl Dimethicone acts as an emulsion stabiliser that keeps water and oil blended, a film former that leaves a soft moisture-sealing veil and a gentle cleanser that lifts grime. It manages these tricks because its silicone backbone spreads smoothly while the fatty and glycerin pieces anchor to skin and attract both oil and a little water.
You will spot it most often in modern multi-tasking creams, primers and cleansing balms though it is still a niche ingredient compared with classic dimethicone or plant oils. Formulators who want lightweight slip without greasy afterfeel reach for it more and more each year.
Current research and decades of safe use in silicones show minimal irritation risk and almost no systemic absorption. Still, everyone’s skin is unique so do a quick patch test when trying any product that lists this ingredient.