Quick question about preservative ratios!

Sorry this may be a dumb question but I have been confused if the percentage you're supposed to use preservative at refer to the water content of the emulsion or the emulsion as a whole as I've seen different sources saying different things. Thanks!


  • PharmaPharma Member, Pharmacist
    Depends on the preservative and the formulation (what's in your water and in your oil phase).
    Very water soluble ones which do not interfere with surfactants may be added in proportion to the water phase, poorly water soluble ones are better added 'calculated from total product'.
  • MelcasMelcas Member
    @pharma thanks so much for clearing that up for me! I was also wondering if I could make my own broad spectrum preservative system using an antimicrobial (such as aspen tree bark extract), an antibacterial (such as ROE), and an anti fungal such as sorbic acid or something. or if I should just buy a premed preservative system? thanks for the help!
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