Ingredient review
Serralysin
INCI: Serratia Peptidase
A gentle enzyme exfoliant that breaks down dead skin proteins without harsh scrubbing, but research in topical skincare is still limited.
In plain English
Serralysin is an enzyme (a type of protein that speeds up chemical reactions) that comes from a bacteria found in silkworms. In skincare, it works like a gentle chemical exfoliant by dissolving the bonds between dead skin cells, helping them slough off naturally. It's much milder than strong acids like glycolic acid, so it's often used for sensitive skin or as a maintenance exfoliant.
Review score
Safety, usefulness, and evidence
Potentially useful with some tradeoffs
The evidence base is still emerging, so marketing claims deserve extra caution.
Risk flags are low for most users, though the finished product can still irritate.
- Source
- biotech
- Evidence
- emerging
- Irritation
- low
- Clogging risk
- low
Quick decision guide
Useful, but context matters
Serralysin 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 Serralysin.
- 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
emergingThe ingredient may be promising, but claims should be treated more cautiously.
What it is
A proteolytic enzyme (protease) produced by the bacterium Serratia marcescens, originally isolated from silkworms. It breaks down proteins into smaller peptides and amino acids.
How it works
When applied to the skin, serralysin cleaves the peptide bonds in keratin and other structural proteins in the outer layer of dead skin cells. This loosens the bonds holding dead cells together, allowing them to shed more easily. It also has mild anti-inflammatory activity by breaking down certain inflammatory mediators.
Pros
Very gentle exfoliation
Serralysin breaks down dead skin proteins without the sting or irritation of AHAs or BHAs, making it ideal for sensitive or compromised skin.
Anti-inflammatory bonus
It may help calm redness and irritation by breaking down inflammatory proteins, which is rare for an exfoliant.
Cons and cautions
Limited topical research
Most studies on serralysin focus on oral use for inflammation. There are few peer-reviewed studies on its effectiveness as a topical skincare ingredient.
Formulation stability
Enzymes are fragile and can lose activity in water-based products or if exposed to heat or extreme pH. Not all products deliver active enzyme.
Best for
- People with sensitive or reactive skin looking for mild exfoliation
- Those who want a non-acid, non-scrub exfoliant for regular use
Use caution if
- Anyone with a known allergy to enzymes or bacterial-derived ingredients
Usage tips
Safety summary
Serralysin is considered safe for topical cosmetic use at low concentrations. It has low irritation and comedogenic potential. However, as with any enzyme, there is a small risk of allergic reaction in sensitive individuals. Patch testing is recommended.
Research notes
Topical serralysin research is sparse. Most evidence comes from oral studies for inflammation. A few small studies suggest it can gently exfoliate and reduce skin roughness, but larger, well-controlled trials are needed to confirm efficacy in cosmetics.
Common label clues
- Typical concentration
- 0.01% to 0.5%
- Regulatory status
- Generally recognized as safe for use in cosmetics in the US and EU when formulated within recommended concentrations. Not approved as a drug.
- Common uses
- Serums, Masks, Cleansers
- Environmental note
- Produced via bacterial fermentation, which is a relatively low-impact biotech process. No known environmental concerns from typical cosmetic use.
Good to know
- Serralysin is also used in oral supplements for inflammation, but topical effects are different.
- It is often labeled as 'Serratia Peptidase' on ingredient lists.
- Enzyme exfoliants like serralysin are pH-dependent and work best near neutral pH.
Common questions
What is Serralysin in beauty products?
Serralysin is an enzyme (a type of protein that speeds up chemical reactions) that comes from a bacteria found in silkworms. In skincare, it works like a gentle chemical exfoliant by dissolving the bonds between dead skin cells, helping them slough off naturally. It's much milder than strong acids like glycolic acid, so it's often used for sensitive skin or as a maintenance exfoliant.
What does Serralysin do in a beauty product?
When applied to the skin, serralysin cleaves the peptide bonds in keratin and other structural proteins in the outer layer of dead skin cells. This loosens the bonds holding dead cells together, allowing them to shed more easily. It also has mild anti-inflammatory activity by breaking down certain inflammatory mediators.
Is Serralysin safe for most people?
Serralysin is considered safe for topical cosmetic use at low concentrations. It has low irritation and comedogenic potential. However, as with any enzyme, there is a small risk of allergic reaction in sensitive individuals. Patch testing is recommended.
Who should be careful with Serralysin?
Anyone with a known allergy to enzymes or bacterial-derived ingredients
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.