Oleyl betaine on your skin: a safety profile

What is oleyl betaine?

The IUPAC name is 1-(oleylammonio)propane-2-sulfonate (zwitterionic form).

Also known as: 1-(oleylammonio)propane-2-sulfonate (zwitterionic form), n-oleyl-N,N-dimethylglycine, ISOALLOXAZINE, 9-(3-DIMETHYLAMINOPROPYL)-, HYDROCHLORIDE, 9-(3-Dimethylaminopropyl)isoalloxazine hydrochloride.

IUPAC name

1-(oleylammonio)propane-2-sulfonate (zwitterionic form)

CAS number

871-37-4

Molecular formula

C21H43NO2

Molecular weight

337.57 g/mol

SMILES

C[NH+](C)CCCC1=C2C(=CC=C1)N=C3C(=N2)NC(=O)NC3=O.[Cl-]

PubChem CID

5362008

Regulatory consensus

1 regulatory bodyhas classified Oleyl betaine.

Regulators apply different standards of evidence — animal-data weighting, exposure-pattern assumptions, epidemiological power thresholds — which is why two scientific bodies can review the same data and reach different conclusions. The disagreement is the data.

Where you encounter oleyl betaine

• specialty shampoo
• premium conditioner
• bath products

Safer alternatives

Lower-risk approaches that achieve a similar outcome to Oleyl betaine:

• Alkyl polyglucosides (APGs) — plant-derived, very mild (e.g., decyl glucoside)
  Trade-offs: Consumer preference for 'natural' label; many natural fragrance compounds are potent allergens (limonene, linalool, eugenol); 'natural' ≠ 'safe'; often more expensive than synthetic equivalents.
  Relative cost: 2-5× conventional
• Amino acid-based surfactants (e.g., sodium lauroyl glutamate, sodium cocoyl glycinate)
  Trade-offs: Extremely mild (pH 5.5-6.5); biodegradable; derived from amino acids and fatty acids; premium ingredient cost; excellent consumer perception; lower foam volume than sulfate surfactants.
  Relative cost: 1.2-2×
• Sodium cocoyl isethionate (SCI) — low irritation potential, solid surfactant
  Trade-offs: Alternative surfactant; performance characteristics (foaming, emulsification, wetting) vary; biodegradability and aquatic toxicity should be assessed; formulation adjustment may be needed.
  Relative cost: 1.2-2×
• Amphoteric surfactants (e.g., cocamidopropyl betaine) — milder than anionic types
  Trade-offs: Removes 95-99% of dissolved contaminants including metals, PFAS, nitrates; wastes 2-4 gallons per gallon produced (improving with newer systems); removes beneficial minerals; $0.05-0.25/gallon; requires pre-treatment for longevity.
  Relative cost: 1.2-2×

Frequently asked questions