Encyclopedia · conditioning agent
Guar hydroxypropyltrimonium chloride
A plant-derived cationic polymer used in conditioning shampoos and "natural" conditioners to ease wet combing; it can build up on hair.
What it is
Guar gum chemically modified with positively charged ammonium groups. It is a cosmetic ingredient widely used in silicone-free "natural" shampoos.
How it works
It binds to negatively charged hair and forms a thick hydrated layer. Streaming-potential work from a polymer maker found that molecular weight sets the thickness of the adsorbed layer and charge density sets the surface charge. Its deposition differs from conventional cationic surfactants like behentrimonium chloride. McMullen 2021
What the studies show
- Guar took up similarly on hair from different ethnic backgrounds, but sorption and desorption of anionic surfactant was quicker on African, grey European and mixed hair than on Chinese, dark European and Indian hair (supplier-run). McMullen 2021
- In a BASF comparison it conditioned well, but build-up and removability were its most striking weaknesses. Hössel 2000
Side effects and safety
We found no hair-specific hazards. The practical issue is film build-up, so clarify periodically.
Bottom line
Reasonable in a natural-leaning shampoo, though fine and low-porosity hair may feel coated. We are only moderately sure, as the evidence is a pair of lab and panel studies.
Studies 2
McMullen RL et al. Investigation of the interactions of cationic guar with human hair by electrokinetic analysis. Int J Cosmet Sci. 2021
Tested: cationic guar compared with behentrimonium chloride and polyquaternium-28
Result: Guar molecular weight set adsorbed layer thickness and charge density set surface charge; anionic surfactant sorption was quicker on African, grey European and mixed hair than on Chinese, dark European and Indian hair.
Read the study ↗Hossel P et al. Conditioning polymers in today's shampoo formulations: efficacy, mechanism and test methods. Int J Cosmet Sci. 2000
Result: Polyquaternium-7, polyquaternium-10 and cationic guar all improved combing, but differed in build-up and removability.
Read the study ↗Related
- Polyquaternium-10A positively charged cellulose polymer that coats hair during shampooing, easing wet combing and helping deliver silicones, with some build-up risk.
- Polyquaternium-7A synthetic positively charged copolymer used in shampoos and rinse-offs to improve wet combing and feel.
- Behentrimonium chlorideA long-chain, positively charged conditioning ingredient that clings to hair and detangles it, with good lab evidence for smoothing and none for repair.
- How conditioner worksRinse-off conditioner coats hair with a positively charged layer that cuts friction and tangling; it does not repair structural damage.