Laurdimonium Hydroxypropyl Hydrolyzed Soy Protein

Laurdimonium Hydroxypropyl Hydrolyzed Soy Protein is a cationic, quaternized hydrolyzed protein used mainly as a conditioning/anti-static agent in hair and rinse-off skin products, typically at low percentages. While hydrolyzed proteins are usually well tolerated, the cationic surfactant-like laurdimonium modification increases binding to skin/hair and can provoke stinging or irritant reactions in compromised barriers (eczema, post-procedure), and soy-derived proteins carry a small but real sensitization/allergen concern in highly reactive individuals. Given the potential for irritation in sensitive populations despite generally low use levels, a mild score is the safest clinically-aligned assessment. Safety Notes: In commercial hair and scalp products this cationic, quaternized hydrolyzed soy protein is most often used at low levels (~0.05–0.3%) as a conditioning/anti-static additive in rinse-off shampoos and conditioners, where deposition is aided by its positive charge. Higher-strength consumer-available leave-on treatments (e.g., spray conditioners, anti-frizz creams, repair masks/serums) commonly push total use levels into the ~0.5–2% range, with a small number of specialized “protein repair/bonding” style products reaching about 3% while still maintaining stability and sensory acceptability. There are no specific FDA/EU maximum concentration limits for this INCI, so the upper end is primarily constrained by formula feel, build-up, and compatibility with other cationic or anionic systems.