What Is Steardimonium Hydroxypropyl Hydrolyzed Keratin?
Steardimonium Hydroxypropyl Hydrolyzed Keratin is a modified form of keratin, the fibrous protein that naturally builds human hair, skin and nails. In this ingredient the keratin protein has first been hydrolyzed, meaning it is broken down into smaller pieces that dissolve easily in water. These fragments are then reacted with a quaternary ammonium compound, specifically 2-hydroxy-3-(octadecyldimethylammonio)propyl chloride. The result is a positively charged, water-compatible molecule that can cling to negatively charged hair and skin surfaces.
The concept of hydrolyzed keratin began gaining traction in salon treatments during the 1970s as stylists looked for ways to repair chemical damage. Chemists later discovered that attaching a quaternary group improved the protein’s ability to bond to hair and resist rinsing, making the material more effective and longer lasting. Today manufacturers create Steardimonium Hydroxypropyl Hydrolyzed Keratin through controlled enzymatic or acid hydrolysis of wool or poultry feathers followed by a quaternization step that neutralizes and purifies the final product.
You will find this ingredient in rinse-off and leave-in hair conditioners, strengthening masks, color-protection formulas, anti-frizz serums, smoothing creams, body lotions and some high-performance facial moisturizers.
Steardimonium Hydroxypropyl Hydrolyzed Keratin’s Cosmetic Benefits/Uses
When added to a formula this multifunctional protein derivative offers several noticeable perks for both hair and skin
- Antistatic: Its positive charge neutralizes static electricity on hair strands helping to reduce flyaways and improve manageability in dry environments
- Hair Conditioning: The small keratin fragments can penetrate damaged cuticles, fill in weak areas and create a smooth protective film that boosts softness, shine and elasticity
- Skin Conditioning: On skin it forms a light moisture-binding layer that enhances smoothness and supports the natural barrier without a heavy feel
Who Can Use Steardimonium Hydroxypropyl Hydrolyzed Keratin
This ingredient is generally well tolerated by all skin types, including dry, normal, combination and oily skin, because it forms a light film without clogging pores or leaving a greasy feel. Very sensitive skin may still prefer a shorter ingredient list but Steardimonium Hydroxypropyl Hydrolyzed Keratin itself is not known to be harsh or highly reactive.
Because the keratin is usually sourced from sheep wool or poultry feathers it is not considered vegan friendly. Vegetarians who avoid animal by-products for ethical reasons may also wish to skip it. Brands sometimes offer plant based protein alternatives, so label readers who follow a vegan lifestyle should look for those instead.
Current safety data shows no special warning for women who are pregnant or breastfeeding when this ingredient is used in rinse-off or leave-on cosmetics applied as directed. Still, this is not medical advice and anyone expecting or nursing should review their personal product lineup with a doctor to be sure each choice aligns with individual health needs.
Steardimonium Hydroxypropyl Hydrolyzed Keratin is not photo-reactive and will not make skin or hair more sensitive to sunlight. It also plays well with common actives such as vitamin C, niacinamide and mild acids, so routine layering is rarely a problem.
Potential Side Effects/Adverse Reactions
Reactions to topical Steardimonium Hydroxypropyl Hydrolyzed Keratin vary from person to person. The points below outline potential side effects, but most users will not experience them when the ingredient is used at standard cosmetic levels in a properly formulated product.
- Mild skin redness or itching, especially on very sensitive skin
- Eye irritation if the product accidentally gets into the eyes
- Scalp buildup leading to dull hair when heavy leave-in concentrations are used frequently without thorough washing
- Allergic contact dermatitis in individuals who are allergic to wool or feather proteins
If any discomfort or unusual reaction occurs stop using the product and seek guidance from a healthcare professional.
Comedogenic Rating
Rating: 1/5
Steardimonium Hydroxypropyl Hydrolyzed Keratin is water soluble and forms a lightweight, breathable film rather than an occlusive layer. Its positively charged structure helps it rinse cleanly, leaving minimal residue that could block pores. Because of this low likelihood of clogging, it earns a near-non-comedogenic score.
Suitable for acne-prone or breakout-prone skin in most formulations.
As with any film-forming ingredient, very heavy leave-on use without proper cleansing can theoretically trap debris on the skin, though this is uncommon.
Summary
Steardimonium Hydroxypropyl Hydrolyzed Keratin is a hydrolyzed keratin protein quaternized to carry a positive charge. It conditions hair by filling in damaged cuticles, reduces static by neutralizing negative charges on strands and lightly moisturizes skin by forming a flexible protein film. These actions translate to softer shinier hair and smoother hydrated skin.
While not as widespread as classic silicones or plant oils, this ingredient shows up often in salon-quality conditioners, strengthening masks and some premium facial creams thanks to its targeted repair claims.
Current research classifies it as low risk with only rare irritation or allergy reports. Still, whenever you introduce a new product it is smart to perform a quick patch test to confirm personal compatibility.