PEG/PPG-18/18 Dimethicone

PEG/PPG-18/18 Dimethicone is a silicone-based surfactant/emulsifier used at low-to-moderate levels to improve spread, reduce tack, and stabilize formulas; it is generally non-reactive and tends to be well tolerated even in barrier-impaired skin. Clinical experience and patch-test data for silicones and PEG/PPG-modified silicones show low irritancy and low sensitization potential, with reactions being uncommon and usually tied to overall formula irritation or compromised skin rather than the ingredient itself. Given rare but plausible irritation in highly reactive eczema patients (especially if the formula is otherwise sensitizing), it fits best as very gentle rather than inert. Safety Notes: PEG/PPG-18/18 Dimethicone (a silicone polyether emulsifier/surfactant) is observed at very low levels (~0.05–0.2%) in leave-on lotions/serums primarily as a minor emulsifier, wetting/feel modifier, or to aid dispersing silicones and UV filters. Typical O/W creams, sunscreens, primers, and hair-conditioning leave-ons commonly use ~0.5–3% to stabilize emulsions and improve slip/spread, while higher-strength consumer-available silicone-heavy primers, makeup bases, and water-resistant sunscreen systems can reach ~5–8% as part of the primary emulsifier/structuring package (above this, aesthetics and formulation balance usually limit use in OTC products).