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Hydrolyzed Keratin in skincare
Hydrolyzed protein from hair/wool; temporarily fills damaged hair cuticle; reduces breakage.
Used in shampoos, conditioners, and leave-in treatments. AM and PM appropriate. In rinse-off products, provides temporary strengthening and smoothing benefits. In leave-in treatments, provides longer-lasting surface repair. Molecular weight determines penetration depth. Smaller hydrolyzed fragments (< 1,000 Da) can penetrate the cortex; larger fragments coat the cuticle.
What it is
Hydrolyzed Keratin is hair protein (from wool, human hair, or feathers) that has been broken down by chemical or enzymatic hydrolysis into smaller peptide chains and amino acids that can interact with hair structure. Mechanism: the smaller protein fragments (200–10,000 Da) adsorb onto damaged sites on the hair cuticle and cortex, temporarily filling in structural gaps, smoothing the cuticle surface, reducing friction and static, and improving tensile strength. Effects are temporary (removed by subsequent washing) but visibly improve manageability, shine, and elasticity. Clinical studies show measurable reduction in hair breakage and improved combability. Also provides some benefit to skin in rinse-off products. Sensitization from hydrolyzed wheat or oat proteins has been documented (particularly in Europe via shampoos), but hydrolyzed keratin allergy is rare. CIR reviewed as safe. Used at 0.1–5% in hair care products.
The facts
| Category | Protein (Hydrolyzed Hair Protein) |
| Typical use | Morning and evening |
| Concentration YARAI treats as a full dose | 5% |
Why the amount matters, not just the presence
Most ingredient checkers tell you whether something is in the bottle. That is a smaller question than it sounds. Hydrolyzed Keratin at 5% and hydrolyzed keratin at a trace level are not the same ingredient in any way that affects your skin.
An ingredient list is ordered by quantity, so position carries real information. YARAI reads that position and scores accordingly, which is why the same ingredient can land differently in two different products.
The honest limit: a list gives order, not percentages. Estimating concentration from position is an estimate. It is a better estimate than ignoring position, and it is still an estimate. We would rather tell you that than let a number look more certain than it is.
Common questions
What does hydrolyzed keratin do in a skincare product?
Hydrolyzed protein from hair/wool; temporarily fills damaged hair cuticle; reduces breakage.
How much hydrolyzed keratin should a product contain?
YARAI treats 5% as a full dose for this ingredient. Below that, the ingredient is present but is scored as contributing less. An ingredient list gives you the order of ingredients, not their percentages, so this is an estimate read from position rather than a measurement.
When should I use hydrolyzed keratin?
Used in shampoos, conditioners, and leave-in treatments. AM and PM appropriate. In rinse-off products, provides temporary strengthening and smoothing benefits. In leave-in treatments, provides longer-lasting surface repair. Molecular weight determines penetration depth. Smaller hydrolyzed fragments (< 1,000 Da) can penetrate the cortex; larger fragments coat the cuticle.
Check your own products
Point your camera at a product. YARAI identifies it from the label, finds that product's full ingredient list from published sources, and scores it. No barcode and no box needed, which is how it handles imported and small-brand products.
Concern level, category and thresholds on this page are read directly from the same data the YARAI app scores with, so this page and the app cannot disagree. EU figures cite Regulation (EC) No 1223/2009. Last built 2026-09-09. Nothing here is medical advice.