Allantoin Recrystalization

edited November 2013 in Formulating
I have had several lotions with allantoin recrystalization. I've read conflicting things about how to prevent this - some said it must be heated above a certain temperature to ensure it has all dissolved, some said it is about the rate of cooling (faster or slower is better, I think I've read both). Anyone know how to prevent this reliably? Thank you!
- If you're not the lead dog, the view never changes -


  • As per the literature available I think it should be added below 50°C, at higher temperatures it will dissolve and recrystallize on cooling. So the trick is I think prolonged mixing (dispersion) to a very fine particle size and which cannot be felt during application. 
    Hope this helps. 
  • You could also try reducing the amount that you use.  Is the allantoin having a noticeable effect in the performance of your product? 
  • @Perry the allowable limit it 0.5-2.0%, even at low concentration it is effective. So if he wants to use it he can lower the limit but the process has to be the same as I previously mentioned.
  • What is it effective at doing?
  • Try it at 0.5% - it should be fine at that level.
    Jane Barber & The Advanced Cosmetic Formulators Club 
    Formulation discussion forum (15,000 members):
  • @Perry it is a skin protectant and anti-irritant, rest of the claims are too complex to just accept them at face value.
  • Allantoin hs been associated with wound healing. The evidence is inferred by the fact that maggots exude it, and maggots are very good at cleaning up septic wounds. It's even a proper recognised medical therapy for bed sores. (How the diet going ?) :D

    I've usually gone to lower concentrations than 0.5%, typically 0.1-0.2% not had any problems with recrystallisation. (I know that the data says that 0.5% is soluble, I've found it difficult to get that all into a hot water phase - YMMV)

    At 0.5% I did see one very old product have crystals in it. Came in as a glass complaint. The product was at least 3 years old, not seen the problem since


    UK based, Over 20 years in Toiletries, After a 5 year sabbatical doing cleaning products, back in the land of Personal Care
  • edited November 2013
    @milliachemist - right. I just wonder what level has to be added for a consumer to notice a difference in the performance of the product. When will a consumer definitely see a difference, at 1%, 0.5%, 0.1%, or 0%?

    From a formulators standpoint you should use the lowest level of an ingredient in which you get a consumer perceptible difference.
  • @Perry I absolutely agree with you, it would need some in vivo testing to check it otherwise for a formulator there is no way to know the quantum of effect of different dosages.
  • Perry - good question! I think I notice the effect at 1%, and probably would at less than that. I feel like it softens the skin after a few minutes - similar to the effect from adding AHAs.

    Thanks everyone for the information. I will try keeping it below 50C and .5% or less.

    Duncan, it does feel like small shards of glass. Not quite as sharp, but similar.

    Thank you!
    - If you're not the lead dog, the view never changes -
  • arctat - yes do experiment with it.  For me, at 0.5% it works if I add it at the very end of the heated water phase. 
    Jane Barber & The Advanced Cosmetic Formulators Club 
    Formulation discussion forum (15,000 members):
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