Home Cosmetic Science Talk Formulating General Salicylic acid acne soap

  • Salicylic acid acne soap

    Posted by Abdullah on February 25, 2021 at 2:57 pm

    %2 Salicylic acid soap is very common for acne treatment. Soap has high pH, Does salicylic acid do its job for acne at high pH?

    According to this chart it is very pH dependent.

    chemicalmatt replied 3 years, 2 months ago 3 Members · 3 Replies
  • 3 Replies
  • RDchemist15

    February 25, 2021 at 4:00 pm

    I was wondering that recently too and found the same information you did. That said there are still drug products being sold that are 2% salicylic acid in high pH soap preparations.

    Might be some useful reading:

    According to this paper salicylic acid at pH 6.50 is just as exfoliating as at pH 3.12. In theory, this is
    likely due to a “time release” technique; where instead of being able to absorb
    the Free acid right away, the inactive form remains on the skin and turns into
    absorbable free acid over time. It should be noted that this applies more to
    leave-on products as a rinsed product would likely not deposit any appreciable
    amount, instead being rinsed away with the soap form being used. There is no
    study unfortunately I can find for high range >7 pH.

    Salicylic acid at ph 7 retains its keratolytic function as similar preparations at pH
    3.3. While, again, not at
    ph 9-10 of soap, the expected free acid levels are practically equivalent so could be
    directly relatable. Important to note that these only apply to BHAs and not AHAs.

  • Abdullah

    February 26, 2021 at 3:52 am

    @RDchemist15 thanks 
    Very informative

  • chemicalmatt

    February 26, 2021 at 3:33 pm

    @RDchemist15 I’ll second that thanks. I always formulated the beta-hydroxyacid desquamators to pH 5 just to prevent the scorching effects on skin at the lower pH, but falsely believed - not any more thanks - that efficacy was diminished as it is for the glycolic acid peels. The 2% SalAc product at pH 5 - 6 is safer with time-release function: a win-win. Also easier to solubilize I might add.

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