kojic acid & glycollic acid cream stability problem

My skin cream formulation contains:
2% kojic acid
5% arbutin
10% glycollic aicd (70%)
0.1% vitamin E

Other ingredients:
Cetosteryl Alcohol, cm 1000, EGMS, Stearic acid, Carbomer940, Triethylamine,
Phenoxy ethanol, Di-sod. EDTA, Benzyl alcohol & silicon oil & Light Liquid Paraffin.

Cream color change started after 8 months form white to pale yellow.
After 18 months it started to become blackish.

Can anybody help?


  • It is packed in Lami. tube. & it has also a leakage problem.

  • i guess kojic acid is not stable, probably an oxidation reaction happens. 
  • You're not using broad spectrum preservatives. Fungi maybe? They come in all colours.
  • Thanks

    Should I test that Blackish for microbes?
    will it help to select preservative.  
  • Yes, you can test it for microbes. 
    What is cm1000 and EGMS btw? I also don't see water mentioned, what is the whole formula? 
    If benzyl alcohol and phenoxyethanol are your only preservatives, I would definitely add an anti-fungal, like paraben(s). Also benzyl alcohol and phenoxyethanol cover more or less the same, maybe you can do with only one of these +anti-fungal/yeast.
  • is the entire product going dark, or just the surface?

    is the discoloration uniform, or does it just happen in irregular patches?

    if possible, a photo would be very helpful
    UK based formulation chemist. Strongest subjects: hair styling, hair bleaches, hair dyes (oxidative and non-oxidative) I know some stuff about: EU regulations, emulsions (O/W and W/O), toothpaste, mouthwash, shampoos, other toiletries
  • It's because oxidation of kojic acid. You can use additional antioxidants. Try sodium hydrogen sulphites
  • Try the dipalmitate salt which is much more stable. On another note, I have done so many of these whitening products. A. That might be a bit aggressive and could have a great deal of inflammation. B. With the multiple raw materials, I imagine you could see some issues with incompatibilities, especially with those actives.

    What is your final demographic and what is there Fitzpatrick rating?
    markfuller@microformulation.com Microformulation.com Microformulation Cosmetic Consulting provides Custom Formulations for both large Commercial accounts as well as smaller entrepreneurs. We can provide Naturally compliant Formulations under the NSF, NPA, Whole Foods and USDA Organic Certifications.
  • Thanks sirs,

    cm 1000 is ceto macrogol & EGMS - Ethylene Glycol Monostearate .
    I use D.M. Water.
    Will use of Sodium Metabisulphite increase stability?
    The cream became brown first & than Blackish from the end of tube.
    I have also added Methyl Paraben & Propyl papraben.
    Image of cream as shown above.

    Thanks again for your Interest & Suggestion.  
  • omg, it looks like chocolate. :D
    Probably the color is more darker at the end because is less cream.
    That is an oxidation issue (I was right finally lol) 
    You can use Kojic Acid Dipalmitate  instead of Kojic acid, it appears more stable.
    "2. Light and Heat Stability Kojic Acid Dipalmitate is light and heat stable, while kojic acid tends to oxidize over time"
  • Thank you all.
    I am going to experiment with sodium metabisulphite & Dipalmitate.
  • You should avoid heat as well. Based on the ingredients you are using, you have a hot emulsion process. Try adding kojic acid at the end of the process when the cream is cool.
    The pH of the cream should be slightly acidic 
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