Kojic acid

Kojic acid is one of the most widely used natural skin-brightening agents, known for its effectiveness in fading dark spots, melasma, and post-acne hyperpigmentation. It is derived from the fermentation of rice or fungi (Aspergillus, Penicillium, or Acetobacter species) and works by inhibiting melanin production.
INCI Name: Kojic Acid
Appearance: White to slightly yellow crystalline powder
Solubility: Soluble in ethanol and glycols
pH Stability: Optimal at 4.0–6.0
Heat Stability: Moderate — avoid prolonged heating above 50 °C
Storage: Light- and heat-sensitive; store in opaque, airtight packaging
Key Cosmetic Benefits

1. Skin Brightening / Depigmenting: Inhibits tyrosinase, the enzyme responsible for melanin synthesis. Gradually lightens melasma, age spots, and post-inflammatory hyperpigmentation.

2. Antioxidant Action: Neutralizes free radicals and prevents oxidative darkening of the skin.

3. Synergy with Other Actives: Works effectively with niacinamide, glutathione, and tranexamic acid for even tone correction.

4. Gentle Exfoliating Effect: Encourages mild cell renewal for clearer, more radiant skin.
   Common Applications
   Brightening serums
   Dark-spot correctors
   Lotions and creams for melasma
   Soaps and cleansers (at low concentrations)
   Formulation Guidelines
   Typical Use Level: 1–2% (up to 3% max for leave-on products)
   pH Range: 4.0–6.0
   Compatibility: Excellent with niacinamide, glutathione, tranexamic acid, panthenol, and allantoin
   Avoid: Very low pH (<3.5) and high temperatures, which can cause oxidation and browning
   Stability Aids: Use antioxidants such as sodium metabisulfite or ascorbyl palmitate, and store in opaque packaging
   Safety Profile
   Non-toxic and non-sensitizing at cosmetic levels. Overuse may cause mild irritation, so it’s best combined with soothing ingredients like panthenol or allantoin. Always follow with sunscreen to prevent rebound pigmentation.
   Formulation Tips
   Combine with niacinamide, tranexamic acid, and glutathione for maximum tone-correction synergy. Maintain formulation pH around 5.0–5.5. Use antioxidants or switch to kojic acid dipalmitate (an oil-soluble, more stable derivative) for better shelf life. Always pair with sun protection during daytime use.