Ingredient review
Zinc Borate
INCI: ZINC BORATE
Zinc borate is a synthetic preservative with antimicrobial properties, but its use in skincare is limited and may cause irritation for sensitive skin.
In plain English
Zinc borate is a man-made ingredient that helps stop bacteria and fungi from growing in cosmetic products, so they last longer. It's not a common skincare ingredient and is more often found in industrial products. Because it can be drying or irritating, it's usually used in very small amounts and not in leave-on products for sensitive skin.
Review score
Safety, usefulness, and evidence
Useful in the right context, but not low-maintenance
The evidence base is useful, but some claims depend heavily on the formula.
Main practical flags: irritation is moderate; clogging risk is low.
- Source
- synthetic
- Evidence
- moderate
- Irritation
- moderate
- Clogging risk
- low
Quick decision guide
Read the cautions before using
Zinc Borate can be useful, but watch for some irritation potential.
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 Zinc Borate.
- 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
moderateCan bother some users, especially with frequent use, damaged skin, or strong companion ingredients.
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
Zinc borate is an inorganic compound made from zinc and boron. In cosmetics, it acts as a preservative and antimicrobial agent, helping to prevent microbial growth in water-containing formulas.
How it works
Zinc borate works by releasing small amounts of zinc and boron ions that disrupt the cell walls and metabolic processes of bacteria and fungi, effectively killing or inhibiting their growth. This helps extend the shelf life of cosmetic products.
Pros
Effective preservative
Zinc borate helps keep cosmetic products free from harmful bacteria and fungi, extending their shelf life and ensuring safety during use.
Broad-spectrum activity
It works against a wide range of microorganisms, making it a versatile option for preserving water-based formulations.
Cons and cautions
Potential irritation
Zinc borate can cause skin dryness, redness, or irritation, particularly for those with sensitive or compromised skin barriers.
Limited skincare research
There is less scientific research on the long-term safety and efficacy of zinc borate in leave-on skincare products compared to more common preservatives.
Best for
- People using products that require a strong preservative system
- Those with non-sensitive, resilient skin who prioritize product longevity
Use caution if
- Individuals with sensitive, dry, or eczema-prone skin
Usage tips
Safety summary
Zinc borate is considered safe for use in cosmetics at low concentrations, but it may cause skin irritation in sensitive individuals. It is not recommended for leave-on products for those with dry or reactive skin.
Research notes
Research on zinc borate in cosmetics is limited. Most safety data comes from industrial or oral exposure studies. Dermatological studies specific to topical cosmetic use are scarce, so its long-term skin safety profile is not fully established.
Common label clues
- Typical concentration
- Typically used at very low concentrations, often below 1%
- Regulatory status
- Zinc borate is allowed in cosmetics in many regions, but its use is often restricted to low concentrations. The EU CosIng database lists it as a preservative with specific concentration limits.
- Common uses
- Preserved formulations, Antimicrobial products
- Environmental note
- Zinc and boron compounds can accumulate in the environment. Disposal of products containing zinc borate should follow local guidelines to minimize ecological impact.
Good to know
- Zinc borate is more commonly used in industrial applications like wood preservation and flame retardants than in cosmetics.
- It is not a typical ingredient in natural or organic skincare lines.
Common questions
What is Zinc Borate in beauty products?
Zinc borate is a man-made ingredient that helps stop bacteria and fungi from growing in cosmetic products, so they last longer. It's not a common skincare ingredient and is more often found in industrial products. Because it can be drying or irritating, it's usually used in very small amounts and not in leave-on products for sensitive skin.
What does Zinc Borate do in a beauty product?
Zinc borate works by releasing small amounts of zinc and boron ions that disrupt the cell walls and metabolic processes of bacteria and fungi, effectively killing or inhibiting their growth. This helps extend the shelf life of cosmetic products.
Is Zinc Borate safe for most people?
Zinc borate is considered safe for use in cosmetics at low concentrations, but it may cause skin irritation in sensitive individuals. It is not recommended for leave-on products for those with dry or reactive skin.
Who should be careful with Zinc Borate?
Individuals with sensitive, dry, or eczema-prone skin
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.