What Is Peg/Ppg-17/18 Dimethicone?
Peg/Ppg-17/18 Dimethicone is a silicone based ingredient created by bonding dimethicone, a familiar soft feeling silicone, with two water loving chains called polyethylene glycol (PEG) and polypropylene glycol (PPG). The numbers 17 and 18 show the average amount of each chain that is attached. This mix of oil friendly silicone and water friendly PEG and PPG lets the ingredient sit comfortably between oil and water, a trait that makes it valuable in skin and hair care.
Silicones first appeared in cosmetics during the 1950s when chemists saw that the silky slip they gave could improve creams and hair products. Over time companies looked for ways to help silicones blend with water based formulas, leading to the development of PEG and PPG modified versions like Peg/Ppg-17/18 Dimethicone during the late 1980s.
The ingredient is manufactured through a controlled reaction that starts with basic sand derived silica. This is turned into dimethicone, then the PEG and PPG chains are added in a step called ethoxylation and propoxylation. The final fluid is filtered and checked for purity before it goes to cosmetic labs.
You will most often spot Peg/Ppg-17/18 Dimethicone in lightweight lotions, daily moisturizers, refreshing gel creams, leave in hair conditioners, primers and sheet mask serums. Because it helps water and oil stay together it can be found in both oil in water and water in oil formulas.
Peg/Ppg-17/18 Dimethicone’s Cosmetic Benefits/Uses
Peg/Ppg-17/18 Dimethicone is mainly valued for its emulsifying power. By positioning itself between oil and water it keeps a formula from breaking or separating, which means creams stay smooth and stable through the life of the product. A stable emulsion also spreads more evenly on skin or hair, giving a consistent feel and finish while helping the active ingredients distribute where they are needed.
Who Can Use Peg/Ppg-17/18 Dimethicone
This silicone-based emulsifier is lightweight and non-greasy so it suits most skin types including oily, combination, normal and even dry or mature skin that needs a smooth finish without heavy occlusion. Sensitive skin generally tolerates it because it is inert and has a large molecular size that stays on the surface, though anyone highly reactive to silicones may prefer to avoid it.
Peg/Ppg-17/18 Dimethicone is made from silica and petrochemical feedstocks with no animal-derived components so it is considered suitable for vegans and vegetarians. As with any raw material, final confirmation rests on the brand’s full supply chain policies but the molecule itself is animal free.
Current safety reviews have not flagged the ingredient as a concern for pregnancy or breastfeeding. It sits on the skin rather than penetrating deeply meaning systemic absorption is extremely low. That said this is not medical advice; anyone who is pregnant or nursing should confirm product choices with their health professional.
The molecule does not make skin more sensitive to sunlight so it is not classed as photosensitising. It can be layered under sunscreen without affecting UV protection and has no known issues with common actives like retinol or vitamin C.
Potential Side Effects/Adverse Reactions
Reactions to topical Peg/Ppg-17/18 Dimethicone vary from person to person. The effects listed below are only potential outcomes and are unlikely for the average user when the ingredient is properly formulated and used as directed.
- Mild redness or itching in individuals who have an existing silicone sensitivity
- Transient clogged pores if layered heavily with other occlusive agents on very oily skin
- Eye irritation if the raw ingredient is accidentally rubbed into the eyes before it is fully diluted in a finished product
- Allergic contact dermatitis, though published cases are exceedingly rare
If any irritation or other unexpected reaction occurs discontinue use and seek advice from a qualified healthcare provider or dermatologist.
Comedogenic Rating
Rating: 1/5
Peg/Ppg-17/18 Dimethicone sits on the surface of skin forming a flexible breathable film that does not block pores in most users. Its large molecular size prevents it from sinking into the follicle where clogging starts, and the PEG-PPG side chains further reduce any greasy residue. For these reasons formulators generally consider it very low on the comedogenic scale, though a tiny percentage of people who are extremely silicone sensitive might notice congestion when the ingredient is combined with heavier occlusives.
Most acne or breakout-prone individuals can use products containing Peg/Ppg-17/18 Dimethicone without added risk of pimples.
If a formula also contains high levels of waxes, butters or certain plant oils, the overall product could still feel heavier and be more pore-clogging even though this specific emulsifier scores low.
Summary
Peg/Ppg-17/18 Dimethicone is a hybrid silicone emulsifier that keeps oil and water united, stabilises textures and gives skin or hair a smooth non-greasy finish. It achieves this by anchoring its oil-loving dimethicone side to oils while its water-loving PEG and PPG chains reach into the aqueous phase, creating a stable bridge between the two.
While not as famous as plain dimethicone or cyclomethicone, it has carved out a solid spot in modern moisturisers, primers and conditioners where a light silky touch is valued.
Current safety assessments class it as low risk with minimal irritation potential and virtually no systemic absorption. It is generally safe for all skin types, but as with any new cosmetic ingredient it is wise to do a quick patch test when trying a fresh product to ensure personal compatibility.