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Moumoujus

OCTOXYNOL-9 CARBOXYLIC ACID.

Valuable CAS 25338-58-3 / SURFACTANT - CLEANSING

Octoxynol-9 Carboxylic Acid is a versatile surfactant widely utilized in cosmetic formulations. It primarily functions as an emulsifying, cleansing, and solubilizing agent, adept at blending oil and water components while also assisting in the purification of skin and hair.

Summary

emulsifying agent surfactant cleansing agent solubilizing agent hydrotrope

Science

Mechanism of Action

This ingredient operates by significantly reducing the surface tension between typically immiscible substances, such as oil and water. Its molecular structure features both lipophilic (oil-attracting) and hydrophilic (water-attracting) regions, which enables it to stabilize emulsions and facilitates the removal of oils and impurities from dermal and hair surfaces by promoting their mixture with water.

Research

Clinical Evidence

Low confidence
Effective range N/A
Optimal

N/A

Key findings

  1. 01 Clinical evaluations on the related compound, Octoxynol-9, at a concentration of 2.0% in formulations, were categorized as moderately to minimally irritating in a 24-hour single-insult, occlusive patch test. Conversely, Octoxynol-9 at 1.0% was classified as a nonirritant in a 4-day patch test involving nine subjects. Furthermore, no skin sensitization was observed in studies evaluating Octoxynol-9 across concentrations ranging from 0.1% to 8.0% in cohorts of 102 to 206 subjects.

Transparency

Dusting Analysis

Not commonly dusted

The Formula

Formulation

Solubility
Both
Optimal pH N/A
0 7 14

Stability

Octoxynol-9 Carboxylic Acid is derived from Octoxynol-9, which is characterized as a stable compound. While a precise optimal pH range for the carboxylic acid derivative's stability was not found, a range of 5.0 to 8.0 has been noted for Octoxynol-5. Formulations incorporating this ingredient should be developed to ensure they are non-irritating. Caution is advised for materials containing appreciably more than 100 ppm free ethylene oxide, as this can present an explosion hazard during storage in closed containers due to gas accumulation.

Conflicts

  • strong oxidizing agents
  • high levels of 1,4-dioxane
  • high levels of ethylene oxide
  • high levels of unreacted C9 phenols

Safety

Safety Profile

CIR Status
Safe as used
Sensitization risk Low

The Cosmetic Ingredient Review (CIR) Expert Panel concluded in 2004 that Octoxynol-9 Carboxylic Acid is safe for use in both rinse-off and leave-on cosmetic products. This assessment was reaffirmed in an amended report in 2025, contingent upon formulations being non-irritating. Although a specific maximum concentration for Octoxynol-9 Carboxylic Acid is not detailed, the related Octoxynol-9 has been reported at up to 2% in skin cleansing preparations (2022 data) and historically up to 5% in leave-on products like cologne. Concerns exist regarding trace levels of impurities such as 1,4-dioxane, ethylene oxide, or unreacted C9 phenols, recommending that these levels be rigorously limited. Ocular irritation was observed at 10% in rabbit studies for Octoxynol-9. The FDA has approved Octoxynols as indirect food additives and Octoxynol-40 as an inactive ingredient in ophthalmic solutions.

Your Skin

Skin Compatibility

No Normal
No Dry
No Oily
No Sensitive
Irritancy Unknown
Comedogenicity Unknown

Our Assessment

Verdict

Valuable

Octoxynol-9 Carboxylic Acid is a valuable surfactant and emulsifier for various cosmetic applications, affirmed as safe by CIR when properly formulated to be non-irritating. While specific irritancy and comedogenicity data for this derivative are unknown, studies on the related Octoxynol-9 indicate potential for irritation and comedogenicity, necessitating careful formulation and impurity control.

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