Hydrolysed keratin

Peptide0.1–2%

Small protein fragments that cling to damaged hair, helping it feel stronger, smoother and less prone to breakage.

What it is

Hydrolysed keratin is the protein of hair and wool, broken into small pieces so it dissolves in water and can attach to hair. It fills weak, damaged spots on the hair surface, so hair feels stronger, smoother and easier to manage. Plant proteins such as wheat, rice, pea and quinoa do a similar job for vegan ranges.

Good for

Damaged hairColoured hairBreakageFrizz

How it works

Damaged hair has gaps and a more negatively charged surface, and protein fragments bind preferentially to these areas. Larger fragments mostly coat the surface and reinforce it, while smaller peptides can reach the inner cortex and help hair hold moisture. A 2021 study found mid- and high-weight keratin peptides made hair fibres stiffer and less prone to breaking.

Ratings

Evidence

3/5

Consistent lab studies on hair fibres, but few consumer trials.

Gentleness

5/5

Very low irritation, and a 2021 review found it safe as used.

Formulation difficulty

2/5

Water-soluble and easy to add, but needs good preservation.

Cost

3/5

Mid-priced, with plant proteins usually cheaper.

Popularity

4/5

'Keratin' is a familiar claim in shampoos, conditioners and masks.

Pairs and cautions

Pairs well with

In a routine. Pairing in one formula depends on matching pH windows.

Panthenol
Amino acids
Conditioning quats
Argan oil
Macadamia oil

Take care with

Formaldehyde-releasing smoothing systemsA different, regulated product type
Hydrolysed wheat protein above 3.5 kDa average peptide weightSensitisation risk, capped in the EU

Formulations it suits

Shampoo Conditioner and hair mask Styling creamHair serum

Packaging

Regional considerations

Australia	No scheduling or concentration limits. Australia is a major wool producer, but confirm the source and country of processing before making a local-ingredient claim.
European Union	Keratin from wool, feathers or horn is unrestricted, but keratin of human origin, such as from human hair, is banned under Annex II, so specify an animal source on the spec sheet.
ASEAN	Indonesia announced on 16 October 2026 that compulsory halal certification for cosmetics is deferred to October 2028. Animal-derived keratin will then need a halal-certified source, or the product must carry a non-halal statement.

In the lab

Specifications

Typical use level

0.1–2%0525%

pH window

pH 4–72 acid7 neutral10 alkaline

Solubility

Water-soluble

Sensitive to

Heat

Shampoos use 0.1–0.5%, and conditioners, masks and leave-ins 0.5–2%, quoted as active protein.

INCI	Hydrolyzed Keratin
Also known as	Keratin protein, Keratin peptides, Keratin hydrolysate, Hair proteins
Origin	animal-derived

Lab notes

Solubility and phase

Water phase. It is often supplied as a 20–30% solution, so dose the raw material for active protein, and quaternised grades give more substantivity in rinse-offs.

Stability

Add below about 60 °C to limit colour and odour, and run a thorough preservative efficacy test, as proteins feed microbes.

Regulatory, Australia

Cosmetic ingredient in Australia (AICIS), with no restriction. CIR (2021) assessed eight keratin ingredients as safe and urged GMP control of impurities in animal-derived material.

Claims to take care with

Cosmetic claims include 'strengthens against breakage', 'smooths' and 'repairs the look of damaged hair', and keratin percentages must be accurate, as the ACCC took action over a '35% natural keratin' claim. Animal origin, usually sheep wool and sometimes feathers or horn, rules out vegan claims.