Peg/Ppg-18/18 Dimethicone: What Is It, Cosmetic Uses, Benefits & Side Effects

Curious about this ingredient? In this article we're explaining exactly what it is and why it's used within cosmetic formulations.
Updated on: July 1, 2025
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We verify all information on this page using publicly available nomenclature standards from The Personal Care Products Council (PCPC), the European Commission's CosIng database and documentation provided directly by ingredient manufacturers. Our analysis is based on technical data from these sources to ensure accuracy and reliability.

What Is Peg/Ppg-18/18 Dimethicone?

Peg/Ppg-18/18 Dimethicone is a hybrid silicone made by attaching two kinds of water loving chains, polyethylene glycol (PEG) and polypropylene glycol (PPG), to a dimethicone backbone. The numbers 18/18 tell us that on average 18 units of each chain are added. The base dimethicone starts as silica, the same mineral found in sand, which is turned into silicone oil. Manufacturers then react this oil with ethylene oxide and propylene oxide to anchor the PEG and PPG groups, creating a molecule that can mix with both oil and water.

Silicones entered beauty formulas in the 1950s for their silky feel and protective qualities. Chemists soon noticed that plain dimethicone repelled water, so they began adding PEG and PPG segments in the late 1970s to help it blend into lotions and creams. Peg/Ppg-18/18 Dimethicone became popular because it lets brands create stable, lightweight textures without greasy residue.

You will most often spot this ingredient in moisturizers, face masks, anti aging serums, sunscreens, makeup primers, liquid foundations, hair conditioners and leave in treatments. Its ability to link oil and water phases makes it a go to choice in both skin and hair care.

Peg/Ppg-18/18 Dimethicone’s Cosmetic Benefits/Uses

This ingredient serves one main purpose in a formula, but that single role brings several noticeable perks for the user.

Emulsifying: Peg/Ppg-18/18 Dimethicone sits at the boundary between oil and water, helping the two stay mixed so a product stays smooth from the first pump to the last. A stable emulsion feels lighter, spreads more evenly and delivers active ingredients more consistently. Because the molecule has both oil loving and water loving parts, it also leaves a soft, velvety finish on skin and hair without a heavy or oily after feel.

Who Can Use Peg/Ppg-18/18 Dimethicone

This silicone-based emulsifier suits almost every skin type. Dry and sensitive skin benefit from the soft, cushioning feel while oily and combination skin appreciate the weightless finish that will not add extra grease. Because the ingredient is considered noncomedogenic, it is unlikely to clog pores, although people who know they react poorly to silicones in general may still prefer to avoid it.

Peg/Ppg-18/18 Dimethicone is produced through synthetic chemistry and contains no animal by-products, so it is suitable for both vegans and vegetarians.

The molecule is large and designed to sit on the surface rather than penetrate, so it is not expected to reach the bloodstream. Current safety reviews rate it as low risk for pregnant or breastfeeding women, but this is not medical advice. Anyone who is expecting or nursing should run the full ingredient list of their products past a doctor to be safe.

The ingredient does not make skin more sensitive to sunlight and can be used morning or night without raising the risk of sunburn. It also works well on all hair textures, including color-treated strands, because it will not strip dye.

Potential Side Effects/Adverse Reactions

Reactions to topical Peg/Ppg-18/18 Dimethicone vary from person to person. The points below list potential issues that could occur, but they are uncommon when the ingredient is used at normal levels in a well-formulated product.

  • Mild skin irritation – a small number of users may notice redness, itching or a stinging sensation
  • Allergic contact dermatitis – very rare cases of true allergy have been reported with silicones in general
  • Breakouts in acne-prone skin – although noncomedogenic, any occlusive layer can sometimes trap sweat and oils leading to pimples in sensitive individuals
  • Product build-up on hair – repeated use without proper cleansing can leave strands feeling weighed down or dull

If you experience any discomfort, stop using the product and speak with a healthcare professional or dermatologist for guidance.

Comedogenic Rating

Rating: 1/5 (low)

Peg/Ppg-18/18 Dimethicone stays on the surface forming a breathable film that lets water vapor pass while keeping skin feeling silky. Its bulky structure means it cannot wedge into pores the way heavier oils sometimes do, so it is classed as low clogging. That said, any film former can trap sweat or debris if the rest of the formula is heavy or if makeup is not removed thoroughly.

Because the ingredient itself is considered low risk for pore blockage, most people prone to acne or breakouts can use it without issue.

Keep in mind the overall product matters: rich waxes, butters or poorly balanced emulsions can raise the chance of congestion even when this silicone alone would not.

Summary

Peg/Ppg-18/18 Dimethicone is an emulsifier that lets oil and water blend smoothly, giving creams, serums and conditioners a lightweight, velvety feel. It achieves this by pairing a dimethicone spine with PEG and PPG chains that reach into both phases, stabilizing the mix and preventing separation.

The ingredient is popular with formulators because it delivers slip and spreadability without a greasy afterfeel, helping products look elegant on the shelf and pleasant on the skin. It turns up in everything from daily moisturizers to high performance sunscreens and hair masks, though it is not as headline grabbing as newer actives.

Safety evaluations rate it as low irritation, low sensitization and low comedogenicity, so it is generally safe for regular use. As with any cosmetic ingredient it is wise to patch test a new product first to make sure it agrees with your unique skin.

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