What Is Isostearyl Carboxydecyl Peg-8 Dimethicone?
Isostearyl Carboxydecyl Peg-8 Dimethicone is a silicone-based ingredient created by linking lightweight dimethicone with isostearyl alcohol, a fatty substance derived from plant oils, and attaching a short chain of polyethylene glycol units. This hybrid structure gives it both oil-loving and water-loving parts, allowing it to mingle easily with a wide range of cosmetic ingredients. First introduced in the early 2000s as formulators searched for silicones that rinse off more cleanly than older heavy grades, it quickly gained popularity in everyday skin and hair products.
The manufacturing process involves reacting dimethicone with ethylene oxide to add approximately eight oxygen-rich units, then esterifying the modified silicone with isostearyl and carboxydecyl groups. The result is a silky fluid that spreads effortlessly and washes away without leaving a heavy film.
You will most often find Isostearyl Carboxydecyl Peg-8 Dimethicone in facial cleansers, two-in-one makeup removers, lightweight moisturizers, sheet masks, primers and hair conditioning sprays where a fresh non-greasy finish is important.
Isostearyl Carboxydecyl Peg-8 Dimethicone’s Cosmetic Benefits/Uses
This ingredient earns its spot on an ingredient list by performing two key jobs that improve how a formula looks, feels and works.
- Cleansing: Its balanced oil-and-water friendly structure helps lift makeup, sunscreen and daily grime from the skin then allows them to rinse away with water so skin feels clean yet comfortable
- Emulsifying: It keeps water-based and oil-based ingredients blended into a stable silky emulsion preventing separation while giving the finished product a smooth glide and lightweight afterfeel
Who Can Use Isostearyl Carboxydecyl Peg-8 Dimethicone
Because it is a lightweight silicone that rinses clean, Isostearyl Carboxydecyl Peg-8 Dimethicone suits most skin types including oily, combination, normal and dry. Those with very dry or compromised skin may want richer occlusives for extra moisture but the ingredient itself is not known to cause additional dryness. Sensitive skin generally tolerates it well since it is non reactive and fragrance free.
The compound is synthesized from plant derived fatty alcohols and petrochemical silicones with no animal sourced components so it is considered suitable for vegans and vegetarians.
No data links this ingredient to hormonal activity or fetal risk. Based on its inert profile it is viewed as safe for topical use during pregnancy and breastfeeding, however this is not medical advice and anyone who is pregnant or nursing should review every product with their healthcare provider.
Isostearyl Carboxydecyl Peg-8 Dimethicone does not make skin more sensitive to sunlight and there is no need for extra sun protection beyond normal daily SPF habits.
Potential Side Effects/Adverse Reactions
Side effects from topical use of Isostearyl Carboxydecyl Peg-8 Dimethicone can vary from person to person. The following are potential reactions that could occur, yet most users will not experience them when the ingredient is properly formulated in a product.
- Mild transient stinging on very sensitive or freshly exfoliated skin
- Redness or itch if an individual is allergic to silicones
- Temporary clogged pores in those extremely prone to congestion when used in leave-on formulas
- Eye irritation if product accidentally enters the eye
If any irritation or unwanted reaction develops stop using the product and consult a healthcare professional if symptoms persist.
Comedogenic Rating
Rating: 1/5
Isostearyl Carboxydecyl Peg-8 Dimethicone is a lightweight PEG-modified silicone that spreads thinly and rinses off easily so it has little chance to settle in pores. Its molecule is too large to penetrate deeply and it forms a breathable film that does not trap significant amounts of oil or debris. Lab data and real-world feedback show a very low incidence of pore blockage, giving it a near non-comedogenic profile.
Because of this low score it is generally considered suitable for people prone to acne or blackheads, especially in rinse-off cleansers and sheer lotions.
Formulas that pair this ingredient with heavy waxes or butters could still feel occlusive so the overall product composition matters most.
Summary
Isostearyl Carboxydecyl Peg-8 Dimethicone acts as a gentle cleanser and a reliable emulsifier. The silicone backbone provides slip while the attached fatty and PEG pieces let it latch onto both oil and water so it can lift grime then keep a formula blended and silky.
It is not as famous as classic dimethicone yet formulators appreciate its clean rinse and weightless feel which is why it shows up in modern gel cleansers makeup removers and airy moisturizers.
Current research and decades of safe cosmetic use point to a very low risk of irritation or toxicity. Still skin is personal so it is smart to patch test any new product that contains it before applying widely.