Ingredient review
PG-Hydrolyzed Keratin
INCI: PG-Hydrolyzed Keratin
A gentle protein ingredient that can temporarily strengthen hair and help skin feel smoother, but effects are not permanent.
In plain English
PG-Hydrolyzed Keratin is a protein derived from keratin (the same protein found in hair, skin, and nails) that has been broken into smaller pieces and attached to propylene glycol so it can mix with water. In skincare and haircare products, it forms a thin film on the surface of hair or skin, temporarily filling in gaps and making strands feel stronger and skin feel smoother. Think of it like a temporary patch that smooths the outer layer, but it washes off over time.
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
PG-Hydrolyzed 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 PG-Hydrolyzed 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
A semi-synthetic ingredient made by breaking down natural keratin (often from wool or feathers) into smaller peptides and then attaching them to propylene glycol. This makes the protein water-soluble and easier for products to spread.
How it works
When applied, the small keratin peptides bind to the surface of hair or skin, filling in damaged areas and forming a protective film. This film reduces water loss, smooths the cuticle, and temporarily strengthens the hair shaft. On skin, it helps retain moisture and leaves a silky feel.
Pros
Temporary strengthening
Fills in gaps in the hair cuticle, making strands feel stronger and less prone to breakage until the next wash.
Improves manageability
Smooths the hair surface, reducing tangles and frizz, and makes hair easier to style.
Cons and cautions
Not permanent
The protein film washes off with shampoo, so benefits last only until your next wash.
Potential buildup
Overuse on fine or low-porosity hair can lead to stiffness or dullness from protein overload.
Best for
- People with damaged, brittle, or over-processed hair
- Those looking for a temporary smoothing or strengthening boost
Use caution if
- Individuals with known allergies to wool or animal-derived proteins (check source)
Usage tips
Safety summary
PG-Hydrolyzed Keratin is considered safe for topical use in cosmetics at typical concentrations. Rare allergic reactions are possible, especially in individuals with wool allergies. It is not known to be irritating or comedogenic.
Research notes
Studies show that hydrolyzed keratin can improve hair strength and moisture retention by forming a protective film. Evidence is mostly from in vitro and small human studies; more large-scale trials are needed.
Common label clues
- Typical concentration
- 0.5% to 5%
- Regulatory status
- Approved as a cosmetic ingredient in the EU, US, and most major markets. No specific restrictions beyond general cosmetic safety requirements.
- Common uses
- Shampoos, Conditioners, Hair masks, Leave-in treatments, Serums
- Environmental note
- Sourcing from wool or feathers uses animal by-products, which may be a concern for some consumers. Plant-based alternatives exist.
Good to know
- PG-Hydrolyzed Keratin is often derived from wool or feathers, so vegans may prefer plant-based protein alternatives.
- It is considered safe for most skin types and is rarely irritating.
Common questions
What is PG-Hydrolyzed Keratin in beauty products?
PG-Hydrolyzed Keratin is a protein derived from keratin (the same protein found in hair, skin, and nails) that has been broken into smaller pieces and attached to propylene glycol so it can mix with water. In skincare and haircare products, it forms a thin film on the surface of hair or skin, temporarily filling in gaps and making strands feel stronger and skin feel smoother. Think of it like a temporary patch that smooths the outer layer, but it washes off over time.
What does PG-Hydrolyzed Keratin do in a beauty product?
When applied, the small keratin peptides bind to the surface of hair or skin, filling in damaged areas and forming a protective film. This film reduces water loss, smooths the cuticle, and temporarily strengthens the hair shaft. On skin, it helps retain moisture and leaves a silky feel.
Is PG-Hydrolyzed Keratin safe for most people?
PG-Hydrolyzed Keratin is considered safe for topical use in cosmetics at typical concentrations. Rare allergic reactions are possible, especially in individuals with wool allergies. It is not known to be irritating or comedogenic.
Who should be careful with PG-Hydrolyzed Keratin?
Individuals with known allergies to wool or animal-derived proteins (check source)
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.