Ingredient review
Lactoperoxidase
INCI: Lactoperoxidase
Lactoperoxidase is a gentle, milk-derived enzyme used as a natural preservative to help keep skincare products fresh without harsh chemicals.
In plain English
Lactoperoxidase is an enzyme that comes from milk and is also found in your saliva and tears. In skincare, it works like a tiny bodyguard: when it meets a little bit of hydrogen peroxide (which is added separately), it creates mild antimicrobial compounds that stop bacteria and fungi from growing in your product. This means your moisturizer or serum stays fresh longer without needing strong synthetic preservatives. It's very gentle on skin and is often used in 'natural' or 'clean' beauty formulas.
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
- natural
- Evidence
- moderate
- Irritation
- low
- Clogging risk
- low
Quick decision guide
Useful, but context matters
Lactoperoxidase 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 Lactoperoxidase.
- 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
Lactoperoxidase is a natural enzyme (a protein that speeds up chemical reactions) originally isolated from milk. It is part of the body's own antimicrobial defense system, found in saliva, tears, and breast milk. In cosmetics, it is used as part of an enzyme-based preservative system, typically paired with glucose oxidase and small amounts of glucose and iodide or thiocyanate to generate low levels of antimicrobial compounds.
How it works
In a cosmetic product, lactoperoxidase works with a partner enzyme (like glucose oxidase) that produces tiny amounts of hydrogen peroxide. Lactoperoxidase then uses that hydrogen peroxide to convert naturally present thiocyanate or iodide ions into antimicrobial compounds (hypothiocyanite or hypoiodite). These compounds attack the cell walls and membranes of bacteria, yeast, and mold, preventing them from growing and spoiling the product. The system is self-limiting and produces only very low, safe levels of these active compounds.
Pros
Gentle natural preservation
Lactoperoxidase offers a mild way to keep products fresh without the irritation that some synthetic preservatives can cause, making it ideal for sensitive skin formulas.
Mimics skin's own defenses
This enzyme is part of the body's natural antimicrobial system in saliva and tears, so it feels familiar and biocompatible on skin.
Cons and cautions
Requires precise formulation
Lactoperoxidase doesn't work alone — it needs partner enzymes and specific substrates to function, which makes formulating with it more complex and less flexible.
Not vegan-friendly
Since lactoperoxidase is typically sourced from cow's milk, it is not suitable for vegan consumers or those avoiding animal-derived ingredients.
Best for
- People with sensitive or reactive skin who prefer gentle preservative systems
- Those looking for 'clean' or naturally-derived skincare products
Use caution if
- Vegans or those avoiding animal-derived ingredients
- Anyone with a known allergy to milk proteins (though purified lactoperoxidase is highly processed and unlikely to trigger allergy)
Usage tips
Safety summary
Lactoperoxidase is considered very safe for topical use. It is non-irritating, non-sensitizing, and non-comedogenic. The enzyme system produces only low levels of antimicrobial compounds that are quickly neutralized by the skin. Allergic reactions are extremely rare, especially given the high purity of cosmetic-grade lactoperoxidase.
Research notes
Research supports lactoperoxidase as an effective antimicrobial agent in cosmetic and oral care products. Studies show it can inhibit a broad range of bacteria and fungi when properly formulated. Its safety profile is well-established, with decades of use in food preservation and oral care. However, most studies are industry-funded, and independent clinical data on cosmetic efficacy is limited.
Common label clues
- Typical concentration
- 0.001% to 0.1%
- Regulatory status
- Lactoperoxidase is generally recognized as safe for use in cosmetics in the EU, US, and many other regions. It is not classified as a preservative by all regulators but is accepted as a functional ingredient with antimicrobial properties. Always check local regulations as they vary.
- Common uses
- Natural preservative systems, Oral care products, Skin care formulations
- Environmental note
- Lactoperoxidase is a natural enzyme sourced from milk, a byproduct of the dairy industry. Its production has a relatively low environmental footprint compared to synthetic preservatives, though it is not suitable for vegan formulations.
Good to know
- Lactoperoxidase is often paired with glucose oxidase and small amounts of glucose and iodide in a system sometimes called 'LPOS' (Lactoperoxidase System).
- The antimicrobial compounds it produces (hypothiocyanite) are the same ones your body uses to keep your mouth and eyes healthy.
- Despite being milk-derived, the purification process removes most milk proteins, so it is generally considered safe even for those with mild dairy sensitivities.
Common questions
What is Lactoperoxidase in beauty products?
Lactoperoxidase is an enzyme that comes from milk and is also found in your saliva and tears. In skincare, it works like a tiny bodyguard: when it meets a little bit of hydrogen peroxide (which is added separately), it creates mild antimicrobial compounds that stop bacteria and fungi from growing in your product. This means your moisturizer or serum stays fresh longer without needing strong synthetic preservatives. It's very gentle on skin and is often used in 'natural' or 'clean' beauty formulas.
What does Lactoperoxidase do in a beauty product?
In a cosmetic product, lactoperoxidase works with a partner enzyme (like glucose oxidase) that produces tiny amounts of hydrogen peroxide. Lactoperoxidase then uses that hydrogen peroxide to convert naturally present thiocyanate or iodide ions into antimicrobial compounds (hypothiocyanite or hypoiodite). These compounds attack the cell walls and membranes of bacteria, yeast, and mold, preventing them from growing and spoiling the product. The system is self-limiting and produces only very low, safe levels of these active compounds.
Is Lactoperoxidase safe for most people?
Lactoperoxidase is considered very safe for topical use. It is non-irritating, non-sensitizing, and non-comedogenic. The enzyme system produces only low levels of antimicrobial compounds that are quickly neutralized by the skin. Allergic reactions are extremely rare, especially given the high purity of cosmetic-grade lactoperoxidase.
Who should be careful with Lactoperoxidase?
Vegans or those avoiding animal-derived ingredients Anyone with a known allergy to milk proteins (though purified lactoperoxidase is highly processed and unlikely to trigger allergy)
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.