Lauramidopropyl betaine: properties, uses, pros, cons, safety

Lauramidopropyl betaine is an amphoteric surfactant from the amidopropyl betaine family, predominantly derived from C12 (lauric) chains. In formulation it is valued for improving foam, mildness, and, in many systems, contributing to viscosity building (in a manner dependent on the surfactant “package” and electrolytes).

Synonyms: dodecanamidopropyl betaine (descriptive); lauramido propyl betaine (common-use variant).

INCI: Lauramidopropyl Betaine.

Definition

Lauramidopropyl betaine is a zwitterion (carrying balanced internal opposite charges) that behaves as an amphoteric surfactant: its effective ionic form varies with pH, which contributes to compatibility with anionic, nonionic, and, under certain conditions, cationic surfactants. Commercially it is often supplied as an aqueous solution with a typical active content on the order of ~30–40%, facilitating dosing and industrial handling.

Main uses

Cosmetics

Used as a co-surfactant in cleansers and rinse-off products to: improve foam, reduce the perceived harshness of certain anionics, and support system rheology. The viscosity-building effect is not “automatic”: it depends on salinity, surfactant ratio, process temperature, and the presence of polymers.

INCI functions

Antistatic
Reduces static electricity on hair and skin, helping to limit frizz and improve combability.

Cleansing
Helps remove dirt, sebum, and residues from the surface of skin and hair.

Surfactant – foam boosting
Enhances and stabilizes foam, making cleansing more uniform and improving the sensory feel.

Hair conditioning
Improves softness, slip, and detangling, reducing friction and roughness.

Skin conditioning
Helps keep skin softer and more comfortable, limiting dryness and tightness.

Surfactant – cleansing
Acts as a cleansing surfactant: lowers surface tension and helps solubilize and remove oils.

Viscosity controlling
Adjusts product viscosity (thinner or thicker), supporting stability and ease of application.

Medicine

The Lauramidopropyl betaine, a surface active substance, has been tested in field conditions, in Niger, against Schistosoma mansoni miracidia. Experiments were carried out in artificial ponds of 20 m3, in which conditions were similar, as far as possible, to conditions found in transmission sites. The product showed a satisfactory remanence and the percentage of infected molluscs dropped down to zero with a low (2 ppm) concentration. It is suggested that laurylamidopropylbetaïne could be used into soaps in order to renew constantly the product in washing and bathing places and reduce schistosome transmission (1).

Identification data and specifications

Common name: Lauramidopropyl betaine
English name: Lauramidopropyl betaine

Molecular Formula:    C₁₉H₃₈N₂O₃

Molecular Weight: 342.5 g/mol

CAS number: 4292-10-8
EC/EINECS number: 224-292-6
Technical note: commercial documentation may show variants linked to supply form (aqueous solution) or related registrations; for regulatory use and quality control, supplier documentation (SDS/CoA) prevails.

Physico-chemical properties (indicative)

Functional role and practical mechanism of action

In cleansing systems, Lauramidopropyl betaine helps reduce the perceived irritancy of certain anionic systems, improves foam quality, and can increase viscosity through changes in micellar microstructure, particularly when the system is properly balanced with salts and co-surfactants. In hair products it may also contribute to better wet combability and overall sensorial profile, without behaving as a cationic conditioner.

Formulation compatibility

It is generally compatible with most surfactants used in cosmetic cleansing. The most recurrent watchpoints are:
Electrolyte interaction: it can improve viscosity up to a point, beyond which instability or rheology loss may occur.
Polymer compatibility: some thickeners (especially ionic ones) can cause haze or viscosity changes.
Temperature: in some systems, heat/cold cycles can change clarity and micellar structure.

Use guidelines (indicative)

Use is typical in rinse-off products. Use level is guided by the objective (mildness, foam, viscosity) and by the active content of the supplied raw material (solution). During development, it is best to optimize jointly: surfactant ratio, electrolyte strategy, thickener choice, pH, and sensory target.

Quality, grades, and specifications

For reproducible results, particularly relevant are: active content, salt/solvent profile of the solution, color/odor within specification, and especially control of impurities typical of certain amidopropyl betaine supply chains (a known topic for the family), which can influence tolerability and sensitization potential. In supplier qualification, SDS and CoA should clarify limits and analytical methods.

Safety, regulatory, and environment

As a rinse-off surfactant, the practical safety profile is dominated by the irritation potential of the finished formula (rather than the single ingredient in isolation). Safety assessments available for alkyl betaines and amidopropyl betaines converge on the view that cosmetic use is acceptable when products are formulated to be non-irritant and non-sensitizing, with particular attention to known category impurities and sensitization risk management in the full formula.

Formulation troubleshooting

Unstable viscosity.
Typical cause: suboptimal electrolyte/surfactant balance. Action: retune salts and amphoteric/anionic ratio.

Haze in “clear” formulas.
Typical cause: incompatibility with solubilizers or polymers. Action: adjust solubilizer/thickener and order of addition.

Reports of irritation.
Typical cause: overly aggressive overall cleansing system or inadequately controlled impurities. Action: rebalance surfactants, verify supplier specs, and set tolerability tests on the finished product.

Conclusion

Lauramidopropyl betaine is a reference amphoteric surfactant for cleansing formulations requiring a strong balance between foam, mildness, and rheology support. Critical success factors are: surfactant-system balancing, electrolyte and thickener management, and quality qualification focused also on impurities relevant to finished-product tolerability.

Mini-glossary

Amphoteric: a surfactant that can behave as cationic or anionic depending on pH and formulation environment.
Zwitterion: a molecule with balanced internal positive and negative charges.
Micellar microstructure: the organization of micelles determining viscosity and clarity in cleansers.
GMP: good manufacturing practice; benefit: reduces variability and contamination, improves quality control.

References____________________________________________________

(1) Sellin B, Combes C, Boiteux JP, Sellin E, Marcon MC, Marcou L. Effectiveness of an amphoteric surface agent against Schistosoma mansoni miracidia in field-like conditions in Niger. Ann Parasitol Hum Comp. 1986;61(3):285-8.

 Morris SAV, Xu L, Ananthapadmanabhan KP, Kasting GB. Surfactant Penetration into Human Skin from Sodium Dodecyl Sulfate and Lauramidopropyl Betaine Mixtures. Langmuir. 2021 Dec 7;37(48):14006-14014. doi: 10.1021/acs.langmuir.1c01867. 

Abstract. Surfactant mixtures are used in a variety of personal care and cosmetic applications but are known to be harsh on the skin. The purpose of this study was to examine anionic surfactant penetration into human skin from nonideal surfactant mixtures under short-time exposure conditions that are relevant to realistic exposure scenarios. This was done by measuring the penetration of a radiolabeled probe (14C-SDS) into human cadaver skin in Franz diffusion cells in vitro from the mixtures of sodium dodecyl sulfate (SDS) and lauramidopropyl betaine (LAPB). Monomer and micelle concentrations in the SDS/LAPB/14C-SDS mixtures were predicted using a regular solution theory approximation. We confirmed that the mixtures of SDS and LAPB exhibit nonideal behavior with a net attraction between the two surfactants. Penetration of 14C-SDS into excised human skin from the mixtures of SDS and LAPB was found to decrease in a log-linear manner with increasing mole fraction of LAPB in the bulk solution (R2 = 0.97, p < 0.001). Additionally, the penetration of 14C-SDS into excised human skin from the mixtures of SDS and LAPB was found to correlate linearly and strongly with the predicted values of 14C-SDS monomer concentration in SDS/LAPB/14C-SDS mixtures (R2 = 0.95, p < 0.01). 14C-SDS penetration from the mixed surfactant composition could be quantitatively reconciled with that from an SDS-only composition by postulating a secondary, positive contribution from LAPB related to its own penetration and binding to skin components that increased SDS penetration at low concentrations. This research therefore supports a monomer penetration theory of surfactant penetration into the skin, combined with a measurable impact of favorable surfactant interactions within the tissue.