PEG-33

PEG-33 is a polyethylene glycol used primarily as a solvent/humectant and slip agent, typically present at low-to-moderate percentages in leave-on and rinse-off products. Across clinical patch testing and broad cosmetic use, PEGs of this type have low inherent irritancy, with reactions more often linked to compromised skin barriers or impurities rather than the PEG backbone itself. For severe sensitivities and eczema-prone patients I still treat it as very gentle—not inert—because barrier disruption can increase sting/irritation risk with glycols and solvents in real-world routines. Safety Notes: PEG-33 is used in commercial skincare primarily as a solubilizer/co-solvent and humectant, and at the low end it commonly appears around 0.05–0.5% in leave-on serums/toners to aid fragrance/oily extract solubilization and improve feel. Higher levels are observed in rinse-off cleansers, micellar/cleansing waters, and makeup removers where it can function as a significant co-solvent/humectant and viscosity/clarity aid, with consumer-available formulas reaching ~10–15% in high-solvent cleansing formats. This range reflects real-world formulation practice; very high levels are uncommon in leave-on creams due to tack/feel and solubilization balance, but are feasible in cleansing products.