What Is Bis-Stearyl Dimethicone?
Bis-Stearyl Dimethicone is a specialty silicone that has long, waxy stearyl chains attached to each end of its silicone backbone. This design makes it part liquid and part soft solid, giving it a rich velvet feel on skin. Most silicones come from silica, the same mineral that makes up sand and quartz. Through a series of reactions, chemists turn silica into basic silicone fluids, then link them with stearyl groups derived from plant or animal fats to create Bis-Stearyl Dimethicone.
The ingredient was introduced in the late 1990s as brands looked for silicones that could mimic the cushion of natural oils while keeping the light finish consumers enjoy. Today manufacturers make it in closed reactors where the silicone fluid is first refined, then reacted with stearyl chloride in the presence of a catalyst. The result is a high-purity ingredient that meets cosmetic safety standards.
Thanks to its balance of slip and creaminess, Bis-Stearyl Dimethicone shows up in face moisturizers, body butters, lipsticks, foundations, sunscreens, hair masks and anti-aging serums. It is also common in leave-on hand creams and soothing balms where a soft protective film is welcome.
Bis-Stearyl Dimethicone’s Cosmetic Benefits/Uses
Formulators turn to Bis-Stearyl Dimethicone because it offers several helpful roles in one ingredient
- Film Forming – Creates a flexible, breathable layer on skin or hair that locks in moisture, improves wear time of makeup and helps actives stay put
- Skin Conditioning – Leaves a smooth, silky finish that reduces the look of rough patches and makes skin feel softer to the touch
- Emollient – Fills in tiny gaps between skin cells to reduce water loss, giving immediate softness without a greasy afterfeel
Who Can Use Bis-Stearyl Dimethicone
Bis-Stearyl Dimethicone is generally well tolerated by most skin types. Its light yet cushy feel suits normal and dry skin while its non greasy finish keeps it comfortable on combination and slightly oily skin. Very oily complexions may find it a bit rich in heavy creams but in gels or serums it rarely feels occlusive. Sensitive skin usually handles it well because the molecule is inert and does not penetrate deeply.
The stearyl portion of the ingredient can be sourced from either plant or animal fats. Many suppliers now use plant derived stearyl alcohol so vegans and vegetarians should look for a vegan certified label or ask the brand about sourcing.
No data suggest risks to pregnant or breastfeeding women when Bis-Stearyl Dimethicone is used topically at cosmetic levels. Still, this is not medical advice and anyone who is pregnant or nursing should run their skin care routine past a doctor to be safe.
The ingredient does not increase photosensitivity and has no known interactions with sunscreen filters or common actives like vitamin C or retinoids.
Potential Side Effects/Adverse Reactions
Reactions to topical Bis-Stearyl Dimethicone vary from person to person. The points below cover potential issues yet most users will not experience them when the ingredient is properly formulated.
- Mild redness or itching in those with silicone sensitivity
- Temporary clogged pores if used in very heavy products on extremely oily skin
- Build up on hair shafts that can leave strands dull until shampooed
- Eye irritation if the product accidentally gets into the eyes
If you notice any discomfort stop use and seek advice from a medical professional.
Comedogenic Rating
Rating: 1 out of 5. Bis-Stearyl Dimethicone is a large silicone molecule that sits on the surface rather than sinking into pores and its smooth film allows sebum to escape, so it is considered very low on the clogging scale. The presence of the waxy stearyl ends can add richness, which explains why the score is not a perfect zero, but real world tests rarely link it to breakouts.
Because of this low score it is generally suitable for acne-prone or breakout-prone skin when used in well balanced formulas, especially lighter lotions or serums.
Heavy cream or balm textures that pair Bis-Stearyl Dimethicone with thick butters or waxes could still feel too occlusive for extremely oily skin. Using a thorough cleanser at night minimizes any chance of build up.
Summary
Bis-Stearyl Dimethicone works as a film former, skin conditioner and emollient. Its silicone backbone provides slip and spreadability while the stearyl chains give a soft cushy feel that fills micro-gaps between skin cells, locking in moisture and smoothing roughness. The flexible film it leaves behind also helps makeup last longer and protects hair fibers from friction.
The ingredient sits in the middle of the popularity scale. It is not as common as basic dimethicone yet it is a favorite in premium moisturizers, lip products and long-wear foundations where a velvety afterfeel is desired.
Safety data and decades of use show it is non irritant, non sensitizing and very low on the comedogenic scale. Still, everyone’s skin is unique so it is wise to patch test any new product that contains Bis-Stearyl Dimethicone before regular use.