"Period of time after opening" Calculation

Hello everyone,

I am new at cosmetic industry and I am trying to find out a method that I can calculate the period of time after opening (PAO). In Europe, the regulation say that one product which is stable for 30 months have to has a PAO mark. I read a lot of opinions, but nobody say an exact method. I read about AFSSAPS method, but I didn't understand how it works. The EU Regulation say that the PAO must calculated by these parameters: Microbiological Tests, Stability Tests, Packaging, Consumers that is the product for, the usage of product and the ingredients. If anybody more experienced from me can help me, that will be great.

Thank you for a great forum and website generally. It is very helpfull for me!


  • Bill_TogeBill_Toge Member, Professional Chemist
    edited October 2017
    you've not found an exact method because it is a matter of judgment, and essentially a 'best guess' 

    the key factors are the type and design of the packaging, how the product behaves over a long period when the pack is opened (i.e. will it dry out or otherwise degrade), and the microbiological risk (i.e. can the end-user potentially contaminate the product while it's inside the pack)
    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
  • Thank you Bill for your response!
  • Pumps will last longer than jars because there are no fingers to contaminate the product. So far, I haven't seen anything beyond 18 months for expiration after opening.
  • Just put the open package in normal stability test and check after 6, 9 and 12 months 
  • Thank you @em88 and @chemnc for your answers.
Sign In or Register to comment.