Multiple preservatives in a system

Can we use two or three preservatives up to there upper limit for better preservation? 

Ex: using %1 benzyl alcohol, %1 phenoxyethanol and %0.6 Sodium Dehydroacetate. 
Total %2.6 preservatives?


  • PharmaPharma Member, Pharmacist
    Depends... usually, one uses blends in order to not just broaden the spectrum but also to be able to use lower amounts for the single constituents.
    A preservative (or a blend thereof) should be used at the minimal required amount, not the maximum. Do some microbial contamination testing to figure out how much your product actually requires.
  • AbdullahAbdullah Member
    edited June 2020
    @yes blends are better but my question was is there any rule to not use two preservative to there maximum when we blend them? 

    For example: in Euxyl® k700 which is: Phenoxyethanol 30%, benzyl alcohol 30%, potassium sorbate 15%, tocopherol 15%,  water 15%. The maximum allowed is %1.5, that becomes %0.45 benzyl alcohol and %0.45 phenoxyethanol. 
  • PerryPerry Administrator, Professional Chemist
    Preservative regulations are set based on the total amount in a formula. It doesn't matter if you add the preservative by itself or if it comes in a blend. If you get 0.45% phenoxyethanol from the blend, you could still add 0.55% more phenoxyethanol by itself. 
  • @Perry thanks
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