Cocamidopropylamine oxide (CAO, CAS 68155-09-9) is a mild amphoteric surfactant derived from coconut oil. It is a popular foam booster, thickener and cleansing agent in shampoos, body washes, facial cleansers and household cleaning products. This article reviews its skin safety profile, typical commercial specifications, main applications and practical formulation considerations.
What Is Cocamidopropylamine Oxide?
Cocamidopropylamine oxide belongs to the amine oxide family of surfactants. Its molecule combines a coconut-derived fatty chain with an amine oxide polar head, which gives it amphoteric character: it carries a positive charge in acidic conditions and behaves as a nonionic surfactant in alkaline conditions. This versatility makes CAO compatible with anionic, cationic and nonionic systems, and it is frequently paired with betaines and sulfates to stabilize foam and reduce irritation in rinse-off products.
Skin Safety Profile
CAO is regarded as a mild surfactant with a low potential for skin absorption. Because the molecule is highly polarized and relatively large, it does not easily penetrate the stratum corneum, which is why it is considered acceptable for leave-on products at appropriate concentrations, and is widely used in rinse-off personal care products such as shampoos and shower gels. As with any surfactant, the final safety of a formulation depends on concentration, use pattern, pH and the complete ingredient list. Individuals with very sensitive skin should patch-test new products, and formulators should comply with the cosmetic regulations applicable in their target markets, including ingredient concentration limits where defined.
Typical Commercial Specifications
Commercial CAO is usually supplied as an aqueous solution with an active matter content in the range of 28 to 32 percent. The table below shows a representative specification sheet.
| Test Item | Specification |
|---|---|
| Classification | Amphoteric surfactant / amine oxide |
| Appearance (25 °C) | Clear to slightly hazy viscous liquid |
| Density (25 °C) | 1.02 - 1.06 g/mL |
| Color (Hazen) | ≤ 50 |
| pH (10% aqueous solution) | 6.0 - 8.0 |
| Active matter content | 28.0 - 32.0% |
| Moisture content | ≤ 70.0% |
| Sodium chloride | ≤ 2.0% |
| Free amine | ≤ 0.2% |
| Foam height (Ross-Miles) | ≥ 200 mm |
| Viscosity (25 °C) | 50 - 200 cP |
Common Applications
Foam boosting: CAO increases foam volume and stability in shampoos, shower gels and hand soaps, especially when combined with alkyl ether sulfates.
Thickening: it raises the viscosity of surfactant systems, helping formulators reduce the need for salt or polymer thickeners.
Gentle cleansing: its amphoteric nature lowers the overall irritation potential of blends containing harsher anionic surfactants.
Household cleaning: used in dishwashing liquids, laundry detergents and hard-surface cleaners for its grease-cutting and foam properties.
Industrial and textile applications: acts as a wetting, emulsifying and antistatic agent in selected processes.
Formulation and Usage Considerations
CAO is most effective in formulations with a pH between 5 and 8, which matches the typical pH range of personal care products. It should be added slowly with adequate agitation when incorporated into cold-mix systems. Avoid strong oxidizing agents and prolonged high-temperature storage, which can degrade amine oxides. The recommended use level is commonly 1 to 5 percent active matter in rinse-off products and lower in leave-on products, but the optimum level depends on the target viscosity, foam profile and the rest of the formula.
Frequently Asked Questions
Is cocamidopropylamine oxide safe for sensitive skin?
CAO is considered a mild, low-irritation surfactant and is widely used in products formulated for sensitive skin. However, individual responses vary, so a patch test is recommended for consumers with known sensitivity, and formulators should keep concentrations within regulated or established safe ranges.
What is cocamidopropylamine oxide used for?
It is mainly used as a foam booster, viscosity builder and mild cleansing agent in shampoos, body washes, facial cleansers, baby care products, dishwashing liquids and other personal care and household cleaning formulations.
Is CAO the same as cocamidopropyl betaine?
No. Both are amphoteric surfactants derived from coconut oil, but they belong to different chemical families: cocamidopropylamine oxide is an amine oxide, while cocamidopropyl betaine is a betaine. They are often used together to optimize foam and mildness.
Can cocamidopropylamine oxide be used in leave-on products?
Yes. Because CAO is not easily absorbed by the skin and has a low irritation profile, it is considered acceptable in leave-on products at suitable concentrations, subject to applicable cosmetic regulations.
How should cocamidopropylamine oxide be stored?
Store in sealed containers in a cool, dry place away from direct sunlight and extreme temperatures. Avoid contact with strong oxidizers. If the product freezes, thaw slowly and mix well before use.
Is cocamidopropylamine oxide biodegradable?
Amine oxide surfactants such as CAO are considered readily biodegradable in standard aerobic biodegradation tests, which is one reason they are preferred in environmentally conscious formulations.
