Keratin

KAIR-uh-tin

Conditioning Agent, Film Former, Protein 7/10 Safety CG ApprovedClean Natural Not Vegan

What Is Keratin?

Keratin is the primary structural protein that makes up human hair, nails, and skin. In hair products, it is typically used in hydrolyzed form, meaning it has been broken down into smaller fragments that can penetrate the hair shaft. Keratin treatments and products aim to replenish the protein structure of damaged hair.

Source: Animal sources (sheep wool, feathers, horns) or human hair; some biotech versions are plant-derived

Origin: Natural

Also known as: Hydrolyzed Keratin, Keratin Protein, Cytokeratin

What Does Keratin Do to Your Hair?

Hydrolyzed Keratin fills in gaps and damage along the hair cuticle, temporarily rebuilding the hair's protein structure. Smaller keratin fragments penetrate into the cortex to strengthen the hair from within, while larger fragments coat the surface for smoothing. This dual action restores elasticity, reduces breakage, and adds shine.

Best For

Damaged hair, over-processed hair, heat-damaged hair, chemically treated hair, high-porosity hair

Not Recommended For

Protein-sensitive hair, low-porosity hair, fine hair (if overused)

Concentration Matters

0.1-5%

Hair Type Compatibility

1A Straight Fine
1B Straight Medium
1C Straight Coarse
2A Wavy Fine
2B Wavy Medium
2C Wavy Coarse
3A Curly Loose
3B Curly Tight
3C Curly Corkscrew
4A Coily S-Shaped
4B Coily Z-Shaped
4C Coily Tight
Heat-damaged: Beneficial

Method Compatibility

Curly Girl (CG) Method: Approved
CG Approved
LOC Method

Safety & Regulation

7/10
AvoidCautionSafe

Safe when used topically. Formaldehyde-containing keratin straightening treatments (Brazilian Blowouts) are a separate, serious safety concern and should not be confused with keratin protein products. Overuse can cause protein overload, making hair brittle.

FDA Status: Generally Recognized As Safe

FDA permits use in cosmetics. The FDA has issued warnings specifically about formaldehyde-releasing keratin smoothing treatments, not keratin protein itself.

EWG Score: 1/10

HairAide Verdict

Keratin is an excellent reparative ingredient for damaged and over-processed hair. The key is balance — too much protein can make hair stiff and brittle, so alternate keratin treatments with moisture-focused products. HairAide recommends keratin products for anyone who heat-styles or color-treats regularly.

Products That Contain Keratin

Conditioners, hair masks, reconstructor treatments, leave-ins, shampoos

Alternatives to Keratin

If you want to avoid Keratin, look for products with these ingredients instead:

Hydrolyzed Wheat Protein, Hydrolyzed Silk, Hydrolyzed Rice Protein, Amino Acids

Frequently Asked Questions

Is Keratin safe for hair?

Yes, Keratin has a safety rating of 7/10 and is generally considered safe for use in hair products. Safe when used topically. Formaldehyde-containing keratin straightening treatments (Brazilian Blowouts) are a separate, serious safety concern and should not be confused with keratin protein products. Overuse can cause protein overload, making hair brittle.

Is Keratin bad for curly hair?

Keratin is CG-method approved and is generally considered safe for curly hair.

Is Keratin CG-method approved?

Yes, Keratin is approved for the Curly Girl method.

What can I use instead of Keratin?

Some alternatives to Keratin include: Hydrolyzed Wheat Protein, Hydrolyzed Silk, Hydrolyzed Rice Protein, Amino Acids

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