What it is
PEG-26 Buteth-26 (commonly listed as PPG-26-Buteth-26, CAS 9038-95-3) is a high-molecular-weight block copolymer ether derived from butyl alcohol reacted with ethylene oxide and propylene oxide. It appears as a clear, colorless to pale yellow liquid. In cosmetic formulations it functions primarily as a skin and hair conditioning agent, lending suppleness and manageability, and as a surfactant/oil solubilizer—particularly effective at dissolving fragrance oils into water-based products. It is commonly paired with PEG-40 Hydrogenated Castor Oil to enhance solubilizing performance at low use concentrations. The ingredient is non-greasy and non-sticky, making it suitable for lightweight serums, toners, micellar waters, body mists, and deodorants. It is also FDA-permitted as an indirect food additive and appears on the IFRA Fragrance Transparency List.
Safety & warnings
The CIR panel concluded PPG-26-Buteth-26 is safe as used in cosmetics, including products applied near the eyes and lips. As with other ethoxylated ingredients, trace amounts of 1,4-dioxane (a potential carcinogen) may be present as a manufacturing by-product; however, tested tradename mixtures contained less than 5 ppm dioxane and less than 1 ppm ethylene oxide—well within acceptable safety thresholds. The ingredient shows low dermal absorption and no sensitization concerns at typical cosmetic concentrations. No comedogenicity or significant irritancy has been reported.
Origin & sourcing
Synthetic. Produced by sequential alkoxylation of butyl alcohol with ethylene oxide and propylene oxide under controlled temperature and pressure, yielding a polydisperse block copolymer. No plant or animal-derived raw materials are involved in standard manufacturing.
History
The CIR Expert Panel published a Final Safety Assessment for PPG-26-Buteth-26 (together with PPG-9-Buteth-12, PPG-12-Buteth-16, and PPG-28-Buteth-35) concluding safe use in cosmetics. An Amended Safety Assessment covering butyl polyoxyalkylene ethers as a class was published in 2022, reaffirming the safety conclusion. The ingredient is permitted under EU Regulation 1223/2009 and is registered with AICIS in Australia.
Questions everyone asks
What does PEG-26 Buteth-26 do in a formula?
It acts as a conditioning agent for skin and hair and as a surfactant/solubilizer, most commonly used to dissolve fragrance oils or essential oils into water-based products without leaving a greasy feel.
Is PEG-26 Buteth-26 the same as PPG-26-Buteth-26?
In most cosmetic ingredient databases these names refer to the same compound (CAS 9038-95-3), a butyl-capped block copolymer of ethylene oxide and propylene oxide. The 'PEG' and 'PPG' prefixes both appear in formulator literature for this material.
Is it safe for sensitive skin?
The CIR Expert Panel has assessed this ingredient class as safe for cosmetic use. It is reported to be non-sensitizing and non-irritating, and it has low dermal penetration, making it generally well-tolerated.
What products typically contain this ingredient?
It appears in toners, micellar waters, body mists, deodorants, serums, and hair care treatments, often at low concentrations to solubilize fragrance or improve product texture.