At a glance
- CAS number
- 501-30-4
- INCI name
- Kojic Acid
- Function
- active, antioxidant, preservative
- Typical use level
- 0.5%–2%
- Solubility
- water
- Stable pH
- 3.5–6
CAS number and synonyms are sourced from PubChem. Function, usage levels, pH and compatibility are AI-assisted formulation guidance — verify against your supplier's technical data sheet and applicable regulations before use.
Also known as
kojic acid 5-Hydroxy-2-(hydroxymethyl)-4H-pyran-4-one 5-Hydroxy-2-(hydroxymethyl)-4-pyrone 5-hydroxy-2-(hydroxymethyl)pyran-4-one 5-Hydroxy-2-hydroxymethyl-4-pyrone acido kojico 2-Hydroxymethyl-5-hydroxy-gamma-pyrone 2-(Hydroxymethyl)-5-hydroxy-4H-pyran-4-one Beaute Cleansing Pasds TurmericKojicSoap Surfree Kojic Acid
Compatibility
Works well with:
Niacinamide Alpha Arbutin Glycerin Hyaluronic Acid Lactic Acid Phytic Acid Vitamin E (Tocopherol) Panthenol Allantoin
Use caution with:
Ferric Ions (Iron Salts) Zinc Oxide Titanium Dioxide L-Ascorbic Acid (high conc.) Alkaline pH Buffers Heavy Metal Ions
Kojic acid chelates metal ions (especially iron and copper), forming dark-colored complexes that cause discoloration in finished products; use EDTA or phytic acid as chelating agents to mitigate this. It is unstable above pH 6.0, oxidizing and turning pink/brown, so formulations must be carefully buffered and antioxidants included. High concentrations of ascorbic acid can compete for oxidation pathways and may accelerate degradation of both actives.
Formulation notes
Restricted or regulated in several markets (e.g., Japan limits to 1%, EU requires safety assessment under current framework); known potential sensitizer at higher concentrations. Protect from light and air; nitrogen blanketing and opaque packaging recommended. EU Cosmetics Regulation currently under review for leave-on product restrictions.
Frequently asked questions
What is Kojic Acid?
Kojic Acid is a active, antioxidant, preservative used in cosmetic and personal-care formulation. Typical use level is 0.5%–2%. It is water-soluble. Stable in the pH 3.5–6 range.
What is Kojic Acid used for?
Kojic Acid is used as active, antioxidant, preservative in cosmetic and personal-care formulations.
What is the typical use level of Kojic Acid?
Kojic Acid is typically used at 0.5%–2% in the finished formulation. Always confirm against your supplier's technical data sheet.
What is the CAS number of Kojic Acid?
The CAS registry number for Kojic Acid is 501-30-4. Its INCI name is Kojic Acid.
At what pH is Kojic Acid stable?
Kojic Acid is generally stable in the pH 3.5–6 range.
What ingredients are compatible with Kojic Acid?
Kojic Acid works well with Niacinamide, Alpha Arbutin, Glycerin, Hyaluronic Acid, Lactic Acid, Phytic Acid, Vitamin E (Tocopherol), Panthenol, Allantoin. Use caution when combining it with Ferric Ions (Iron Salts), Zinc Oxide, Titanium Dioxide, L-Ascorbic Acid (high conc.), Alkaline pH Buffers, Heavy Metal Ions.
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