Ingredient review
Carboxymethyl Alanyl Disulfide Keratin
INCI: CARBOXYMETHYL ALANYL DISULFIDE KERATIN
A modified keratin protein that helps strengthen and repair damaged hair by filling in gaps in the hair cuticle.
In plain English
This is a lab-modified version of keratin, the natural protein that makes up your hair. It's been chemically tweaked to better stick to your hair and help repair damage from heat, coloring, or chemical treatments. Think of it as a targeted patch for your hair's outer layer.
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
Carboxymethyl Alanyl Disulfide 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 Carboxymethyl Alanyl Disulfide 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
Carboxymethyl alanyl disulfide keratin is a semi-synthetic protein derived from natural keratin. It has been chemically modified with carboxymethyl groups and disulfide bonds to improve its ability to bind to hair and resist rinsing away.
How it works
When applied to hair, this ingredient forms a thin, flexible film on the surface and can penetrate slightly into damaged areas. The disulfide bonds help it link to the hair's own keratin, filling in gaps and smoothing the cuticle. This reduces frizz, adds shine, and makes hair feel stronger and less prone to breakage.
Pros
Targeted repair
Specifically designed to bond with damaged areas of the hair cuticle, providing more effective repair than standard proteins.
Longer-lasting effects
The chemical modification helps it resist being washed away, so benefits can last through several shampoos.
Cons and cautions
Potential buildup
Frequent use without clarifying can lead to protein buildup, making hair feel stiff or dull.
Not for all hair types
Fine or low-porosity hair may feel weighed down or greasy, especially if used too often.
Best for
- People with damaged, color-treated, or heat-styled hair
- Those seeking smoother, shinier hair with less frizz
Use caution if
- People with very fine or limp hair who may find it heavy
- Those with protein-sensitive hair that becomes brittle with protein treatments
Usage tips
Safety summary
Considered safe for topical use in cosmetics at typical concentrations. Rare reports of mild scalp irritation in sensitive individuals. No known systemic toxicity concerns.
Research notes
Studies show modified keratins can improve hair strength and reduce breakage by up to 30% in damaged hair. Most evidence comes from in vitro and small clinical studies. More research is needed on long-term effects and optimal use.
Common label clues
- Typical concentration
- 0.5% to 5%
- Regulatory status
- Approved for use in cosmetics in the US, EU, and most major markets. No specific restrictions beyond general cosmetic safety requirements.
- Common uses
- Shampoos, Conditioners, Hair masks, Leave-in treatments, Hair serums
- Environmental note
- Keratin is typically sourced from animal byproducts (wool, feathers, or horns). The modification process uses chemical reagents, but the final ingredient is biodegradable.
Good to know
- This ingredient is often listed near the middle or end of an ingredient list, indicating a moderate concentration.
- It works best on damp, clean hair where the cuticle is slightly open.
Common questions
What is Carboxymethyl Alanyl Disulfide Keratin in beauty products?
This is a lab-modified version of keratin, the natural protein that makes up your hair. It's been chemically tweaked to better stick to your hair and help repair damage from heat, coloring, or chemical treatments. Think of it as a targeted patch for your hair's outer layer.
What does Carboxymethyl Alanyl Disulfide Keratin do in a beauty product?
When applied to hair, this ingredient forms a thin, flexible film on the surface and can penetrate slightly into damaged areas. The disulfide bonds help it link to the hair's own keratin, filling in gaps and smoothing the cuticle. This reduces frizz, adds shine, and makes hair feel stronger and less prone to breakage.
Is Carboxymethyl Alanyl Disulfide Keratin safe for most people?
Considered safe for topical use in cosmetics at typical concentrations. Rare reports of mild scalp irritation in sensitive individuals. No known systemic toxicity concerns.
Who should be careful with Carboxymethyl Alanyl Disulfide Keratin?
People with very fine or limp hair who may find it heavy Those with protein-sensitive hair that becomes brittle with protein treatments
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.