Ingredient review
Steardimonium Hydroxypropyl Hydrolyzed Keratin
INCI: Steardimonium Hydroxypropyl Hydrolyzed Keratin
A gentle, positively charged protein that coats hair to reduce frizz and static without weighing it down.
In plain English
This ingredient is a modified protein made from keratin (the same protein that naturally makes up your hair). It has been given a positive electrical charge so it sticks to the negatively charged surface of damaged hair. This helps smooth the hair cuticle, reduce flyaways, and make hair feel softer and easier to comb. Because it's a large molecule, it mostly stays on the outside of the hair shaft rather than penetrating deeply.
Review score
Safety, usefulness, and evidence
Potentially useful with some tradeoffs
The evidence base is useful, but some claims depend heavily on the formula.
Risk flags are low for most users, though the finished product can still irritate.
- Source
- semi synthetic
- Evidence
- moderate
- Irritation
- low
- Clogging risk
- low
Quick decision guide
Useful, but context matters
Steardimonium Hydroxypropyl Hydrolyzed Keratin is generally a lower-concern ingredient when the full formula suits your skin.
Plain-English read
Treat this as a practical screening step before you compare products that contain this ingredient.
- Step 1Start with the score, then check the irritation and clogging risk before judging Steardimonium Hydroxypropyl Hydrolyzed Keratin.
- Step 2Use the "Best for" and "Use caution if" sections to match the ingredient to your skin, not just to a marketing claim.
- Step 3If a product stings, breaks you out, or worsens irritation, judge the finished formula and stop using it even if the ingredient scores well.
Score terms in plain English
Irritation risk
lowLess likely to sting, burn, or bother most users, though sensitive skin can still react.
Clogging risk
lowLess likely to feel heavy or contribute to clogged pores for most skin types.
Evidence level
moderateThere is useful support, but formula details and claim strength still matter.
What it is
A quaternary ammonium compound derived from keratin protein. The 'steardimonium' part adds a positive charge, making it cationic and able to bind to hair's negative surface.
How it works
When applied in a rinse-off or leave-on product, the positively charged molecule electrostatically bonds to the negatively charged areas of damaged hair. This forms a thin, flexible film that smooths the cuticle, reduces static electricity, and improves wet and dry combing.
Pros
Reduces static
The positive charge neutralizes negative charges on hair, reducing flyaways and static cling, especially in dry or winter conditions.
Light conditioning
Unlike heavier oils or silicones, this protein-based ingredient provides a soft, non-greasy feel that doesn't weigh down fine hair.
Cons and cautions
Potential buildup
With repeated use, especially without clarifying shampoos, the protein film can accumulate on low-porosity hair, leading to stiffness or dullness.
Animal-derived source
Keratin is typically sourced from animal wool, feathers, or horns, making it unsuitable for strict vegans or those avoiding animal by-products.
Best for
- People with frizzy or static-prone hair
- Those looking for a lightweight conditioner for fine hair
Use caution if
- Vegans or those avoiding animal-derived ingredients
- Individuals with very low-porosity hair prone to protein overload
Usage tips
Safety summary
Considered safe for topical use at typical concentrations. Rare reports of mild scalp irritation in sensitive individuals. Not known to be comedogenic.
Research notes
Studies on quaternized proteins show effective reduction of combing force and static charge on hair. Most evidence comes from cosmetic chemistry literature rather than large-scale clinical trials.
Common label clues
- Typical concentration
- 0.5% to 3%
- Regulatory status
- Approved for use in cosmetics in the US, EU, and most major markets. No specific concentration restrictions for rinse-off products.
- Common uses
- Shampoos, Conditioners, Leave-in treatments, Hair masks
- Environmental note
- Keratin is a by-product of the wool and meat industry, so its use can be considered upcycling. However, the quaternization process involves synthetic chemicals.
Good to know
- This ingredient is often listed near the end of an ingredient list because it's effective at low concentrations.
- It is compatible with most surfactants and other conditioning agents.
Common questions
What is Steardimonium Hydroxypropyl Hydrolyzed Keratin in beauty products?
This ingredient is a modified protein made from keratin (the same protein that naturally makes up your hair). It has been given a positive electrical charge so it sticks to the negatively charged surface of damaged hair. This helps smooth the hair cuticle, reduce flyaways, and make hair feel softer and easier to comb. Because it's a large molecule, it mostly stays on the outside of the hair shaft rather than penetrating deeply.
What does Steardimonium Hydroxypropyl Hydrolyzed Keratin do in a beauty product?
When applied in a rinse-off or leave-on product, the positively charged molecule electrostatically bonds to the negatively charged areas of damaged hair. This forms a thin, flexible film that smooths the cuticle, reduces static electricity, and improves wet and dry combing.
Is Steardimonium Hydroxypropyl Hydrolyzed Keratin safe for most people?
Considered safe for topical use at typical concentrations. Rare reports of mild scalp irritation in sensitive individuals. Not known to be comedogenic.
Who should be careful with Steardimonium Hydroxypropyl Hydrolyzed Keratin?
Vegans or those avoiding animal-derived ingredients Individuals with very low-porosity hair prone to protein overload
Research sources
Ingredient reviews are educational and are not medical advice. Patch test new products and ask a licensed clinician about persistent irritation, allergies, pregnancy-specific questions, or diagnosed skin conditions.