Hydrolyzed Keratin
Keratin broken into small pieces so it can cling to and partly enter damaged hair. It temporarily fills weak spots, adding strength and body.
About Hydrolyzed Keratin
Keratin is the main structural protein of hair. Hydrolyzed keratin is keratin — usually from wool, feathers or horn — that has been broken down with water, acid or enzymes into much smaller fragments called peptides. Those fragments are small enough to dissolve in water-based products and to stick to the hair surface; the smallest ones can partly enter damaged areas of the cuticle.
In practice it acts as a temporary patch. Hair that has been relaxed, colored, heat-styled or roughly detangled has gaps and weak points, and hydrolyzed keratin helps fill them, which can make strands feel stronger, less mushy when wet and more elastic. It also forms a light film that helps hair hold onto water. The effect washes out over several shampoos, so it needs to be repeated.
It is important to separate this ingredient from 'keratin treatments' at the salon. Those smoothing services rely on other chemistry and heat to straighten hair; a conditioner listing hydrolyzed keratin does not straighten anything.
Who tends to love it: people with relaxed, texlaxed, bleached or high porosity hair, and anyone whose hair stretches and snaps. Who may want to limit it: people with protein-sensitive or low porosity hair, whose strands can feel stiff, straw-like or brittle when protein builds up. If that happens, alternate with protein-free moisturizing products. It is approved for the Curly Girl Method.
How our checker rates it
| Mode | Rating | Why |
|---|---|---|
| Curly Girl | OK | No concerns for this mode. |
| Relaxed hair | Good | Protein — helps reinforce chemically weakened hair. Balance it with moisture. |
| Low porosity | Caution | Protein high in the list can leave low-porosity hair stiff. Use protein sparingly. |
| Protein-sensitive | Avoid | Protein — #1 on the list. |
Ratings assume it is listed near the top of the label. After the first preservative or fragrance (likely 1% or less) most cautions soften.
What protein ingredients do
Hydrolyzed proteins, peptides and amino acids that temporarily patch gaps in the cuticle and add strength. Some hair turns stiff or brittle with too much.
Also listed as
- keratin protein
- hydrolysed keratin
- hydrolyzed keratin protein
- liquid keratin
Similar ingredients
Sources
Last data update:
- Robbins CR. Chemical and Physical Behavior of Human Hair. 5th ed. Springer; 2012. Reference text on hair structure, surfactants, conditioning agents, protein, heat and chemical treatments.
- Gavazzoni Dias MF. Hair cosmetics: an overview. Int J Trichology. 2015;7(1):2-15. Overview of shampoos, conditioners, silicones, straighteners and their effects on the hair shaft.
- Cosmetic Ingredient Review (CIR). Ingredient safety assessments. Safety assessments for cosmetic ingredients cited on ingredient pages.
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