Common Name(s): Oleth-9,peg-9 oleyl ether,peg-9 octadecenol ether

CAS Number: 5401-17-2

DESCRIPTION

What It Does: Helps oil and water mix together in creams and lotions.

Why It's Used: Hlb ~12 from 9 eo on oleyl c18:1; suitable for o/w emulsification; liquid emulsifier due to unsaturated oleyl chain.

How It Works: 9 eo units give hlb ~12; c18:1 oleyl chain provides liquid (non-waxy) character; suitable for o/w emulsification.

Typically Found In: O/w emulsions,creams,lotions,skin conditioning products

TECHNICAL DETAILS

Primary Category: Functional ingredient – emulsifier

Secondary Functions: Emollient,skin conditioning

Application Areas:

Typical Concentration Range: 0.5%–5%

SOURCING & ETHICS

Vegan Status: Conditional - feedstock declaration required

Halal Status: Unverified - feedstock declaration required (plant, animal and petrochemical routes all exist)

Source Notes: Oleyl alcohol from plant (olive/sunflower); eo from petrochemical. [audit 2026-07-29 rev2: origin-dependent: the same inci exists in plant, animal and petrochemical versions and the name does not discriminate. determination requires shariah-panel sign-off.]

SKIN COMPATIBILITY

Irritancy Rating: 1/5 – very low

Comedogenicity Rating: 2/5 – low-moderate (oleyl chain)

Sensitivity Concerns: Generally well tolerated.

Safe for Sensitive Skin: Yes

SAFETY & COMPATIBILITY

Safety Profile: Good safety profile. ewg score: 1–2.

Works Well With: Emollients,fatty alcohols,high-hlb emulsifiers

Avoid Combining With: No significant incompatibilities

SCIENTIFIC NOTE

Oleth-9 hlb ~12 is near optimum for many standard o/w cosmetic emulsions; the oleyl chain keeps the emulsifier liquid at room temperature, making it easy to process; cas 5401-17-2.

Last Verified: 2026-03-27

Primary Sources: Cosing database,inci dictionary