Steartrimonium Bromide

What is Steartrimonium Bromide?

Steartrimonium Bromide is a quaternary ammonium compound, chemically N,N,N-trimethyloctadecan-1-aminium bromide, synthesized from stearic acid and trimethylamine. This cationic surfactant appears mainly in rinse-off hair care items such as conditioners, detanglers, and styling aids. Its positively charged head group electrostatically attracts to the negatively charged hair surface, depositing a hydrophobic layer that lubricates strands, seals cuticles, and diminishes inter-fiber friction. This action neutralizes static buildup from shampooing or brushing, while the long alkyl chain provides a smoothing barrier for better comb-through and reduced tangling. Its inherent antimicrobial nature also supports product stability against microbes. Employed at controlled levels in formulations, it represents a staple in cationic conditioning systems for everyday hair maintenance.

Comedogenic Rating 0/5 Low risk of clogging pores
EWG Safety Rating 4 View on EWG →

Roles in Formulation

This ingredient serves the following purposes in cosmetic formulations:

Antistatic agent
Reduces static electricity and flyaways by improving surface conductivity, enhancing hair manageability and smoothness in conditioners and styling products.
Hair conditioning
Improves softness, shine, and manageability by reducing friction and static; commonly achieved with cationic agents, silicones, oils, or conditioning polymers.
Preservative
Protects the product from microbial contamination during storage and use, helping maintain safety, stability, and shelf life.

Benefits

Minimizes static electricity for flyaway-free hair.

Enhances softness, shine, and ease of styling.

Supports product preservation by inhibiting microbial growth.

Who It's For

A quick guide for who this ingredient may suit (and who should be cautious).

Who May Benefit Who Should Avoid
Individuals with dry, frizzy, or static-prone hair.
Those with known sensitivity to quaternary ammonium compounds.
Users seeking improved manageability in conditioners.
Individuals prone to contact dermatitis from cationic surfactants.
People using styling products for smoother results.
Users of leave-on products if irritation history exists.

Safety Notes

  • Generally considered safe in rinse-off cosmetics at typical use levels.
  • May pose moderate irritation risk, especially to eyes or damaged skin.

Frequently Asked Questions about Steartrimonium Bromide

What does Steartrimonium Bromide do in hair products?

It conditions hair by reducing friction and static while aiding preservation.

Is it safe for daily use?

Safe in rinse-off products at standard cosmetic concentrations per reviews.

Does it clog pores?

Rated non-comedogenic, suitable for hair-focused applications.