Cassia Hydroxypropyltrimonium Chloride
INCI: CASSIA HYDROXYPROPYLTRIMONIUM CHLORIDE
Reviewed by Kate · Last updated 14 Aug 2026
A plant-derived conditioning polymer that improves hair texture and manageability
Best For Skin Types
All
Usage Frequency
As directed by product instructions
What Is Cassia Hydroxypropyltrimonium Chloride?
Cassia hydroxypropyltrimonium chloride is a positively charged polymer derived from cassia plant seeds. It belongs to a class of conditioning agents that work by adhering to the hair fibre surface, where they deposit a protective layer.
In skincare formulations, this ingredient functions primarily as a conditioning and antistatic agent. It is occasionally included in scalp-focused or hair-infused skincare products rather than traditional face serums or moisturisers, though its presence in skincare is relatively uncommon.
How It Works
Cassia hydroxypropyltrimonium chloride is a cationic (positively charged) polymer. Hair fibres have a naturally negative surface charge, so this ingredient is electrostatically attracted to the hair shaft. Once deposited, it forms a thin film that smooths the hair cuticle.
This coating reduces friction between individual hair fibres, which decreases frizz and static electricity. The same mechanism also improves how hair feels to the touch and how it behaves when wet or dry.
Clinical Evidence & References
Research into cassia hydroxypropyltrimonium chloride has primarily focused on its mechanical properties when applied to hair fibres. Studies using cantilever bending techniques have characterised how this polymer alters the flexibility and bending properties of treated hair, confirming its conditioning effect at a structural level.
However, large-scale clinical trials specifically measuring consumer-facing outcomes (such as perceived softness, shine, or manageability) are limited in published literature. The evidence base for this ingredient is strongest in the hair-care category rather than skincare.
How to Use
When present in scalp or hair-focused skincare products, apply according to product instructions. For best results, ensure the product is distributed evenly through damp hair and consider leaving it on for the recommended duration before rinsing. If using a leave-on product containing this ingredient, test a small area first to ensure tolerability.
Safety & Precautions
Frequently Asked Questions
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