AOS in Personal Care: Shampoos, Cleansers and Oral Care

Sodium alpha-olefin sulfonate (AOS, CAS 68439-57-6) is one of the most useful anionic surfactants in personal care. It foams richly, tolerates hard water and is milder than the older sulfates – and because it is a sulfonate made without ethoxylation, it brings none of the 1,4-dioxane concerns of some ethoxylated surfactants. This article covers how AOS is used in shampoos, cleansers, hand soaps and oral care, and how to formulate with it.

1. Why formulators choose AOS

Property	Benefit in personal care
Rich, stable foam	Good lather in shampoos, body washes and hand soaps
Mildness	Lower irritation than SLS; suitable for frequent-use and gentle products
Hard-water tolerance	Performance and foam hold up in hard water
Sulfonate stability	Stable across pH – no sulfate-ester hydrolysis
No ethoxylation	No 1,4-dioxane issue; a clean label story
Good biodegradability	Supports a favourable environmental profile

2. Shampoos, body washes and cleansers

AOS is used as a primary or co-surfactant to build a rich, creamy lather with a mild skin feel. Typical approach:

Role in the formula	Typical choice
Primary anionic surfactant	AOS, or AOS blended with SLES (SLES)
Secondary / mildness booster	Amphoteric (betaine) or nonionic (for example cocamide MEA)
Thickener	Electrolyte (NaCl) or a rheology modifier, matched to the surfactant blend
Conditioning	Cationic polymer or silicone, where needed

Because AOS has a different response to electrolyte and to betaine than SLES, the thickener has to be matched to the blend – build the system and confirm viscosity and foam by test.

3. Hand soaps and hand hygiene

AOS gives hand soaps a rich lather with a mild feel, and its hard-water tolerance keeps foam performance up in everyday use. It is also used in foam-type hand soaps, where it helps produce a stable, quick-lathering foam.

4. Oral care: toothpaste and mouthwash

AOS is a common foaming agent in toothpaste, where it has largely replaced or is blended with SLS. The reason is mildness: SLS is associated with oral irritation (and in some users with aphthous ulcers), while AOS foams well with less irritation. For oral care, choose a grade with low colour and low odour and confirm the assay and impurity limits with your supplier.

5. Formulating with AOS

Parameter	Typical practice
Active level (shampoo/body wash)	About 8 – 15% total active surfactant
Active level (hand soap)	About 5 – 12% active
pH	Near-neutral to mildly acidic (typically pH 5 – 7), adjusted with citric acid
Blend partners	Betaines, cocamide MEA, SLES, SLMI (gentle cleansers)
Grading	Use a low-Klett grade for clear, light-coloured products

Formulate by building the surfactant blend first, then adjust viscosity, pH and preservation – and always confirm mildness and foam on the finished formula, not only on paper.

6. Mildness and safety

Milder than SLS – lower irritation potential, which is why AOS suits frequent-use and oral-care products.
No EO / 1,4-dioxane – AOS is not ethoxylated, so it does not carry that concern.
Biodegradable – readily biodegradable, with a good aquatic profile.
Handling – a surfactant: avoid eye contact and prolonged skin contact; follow the SDS.

7. Which AOS grade?

Grade	Personal-care use
Liquid (34-36%)	Directly into liquid formulations; easiest to pump and blend
Powder (92%)	Powder and solid formulations; also used where shipping liquid is uneconomic

Both grades are the same surfactant at different active levels – pick by the product form and the logistics, not by performance.

Frequently Asked Questions

Is AOS suitable for shampoo?

Yes – it is a common primary or co-surfactant, giving rich foam, hard-water tolerance and a mild feel. It is often blended with a betaine, cocamide MEA or SLES.

Is AOS milder than SLS?

Yes. AOS is generally less irritating than SLS, which is why it is used in gentle cleansers and in toothpaste as a less-irritating foaming agent.

Why use AOS in toothpaste?

For mildness: it foams well with lower oral irritation than SLS, and it avoids the SLS association with mouth ulcers in some users.

Does AOS contain 1,4-dioxane?

No – AOS is not ethoxylated, so it does not carry the 1,4-dioxane concern of some ethoxylated surfactants.