Stability and compatibility test


The cosmetic product stability and compatibility test is required by EU Cosmetics Regulation 1223/2009 and the UK Schedule 34 to the Product Safety and Metrology etc. (Amendment etc.) (EU Exit) Regulations 2019. It is mentioned in part A of annex I of the regulation and is therefore a part of the cosmetic product safety information.

The primary objective of conducting stability testing is to indicate the relative stability level of a product under the various conditions that it can be subjected to from the moment it is manufactured until the end of its validity.

The purpose of the test is to evaluate whether the product will meet the prescribed physical, chemical and microbiological quality standards, and assess its functionality, safety and aesthetics over a period of time during handling, transport and storage under appropriate conditions.

Based on the stability test results, we also assign the shelf life or the period after opening to the product.

The type and quality of packaging used also affects the stability of the product, as it protects the cosmetic product from the external environment.

On the other hand, potential leaching of substances in the packaging into the product must be evaluated. For this reason, compatibility between the packaging and its contents must be investigated, in order to ensure that no quality problems are introduced by the type of packaging material used.

All cosmetic products should be subjected to the stability and compatibility test; there are no exceptions as for the preservative efficacy test. Stability and compatibility tests must be repeated every time there is a change in the formula, packaging or manufacturing process.


The cosmetics stability test can be performed in real time or it can be accelerated. The time that it takes to complete the test and the conditions under which it is performed can vary, as can the parameters that are monitored during the stability and compatibility test.

Real-time stability tests are usually performed at room temperature and take as long as the claimed shelf life on cosmetic product labels.

Due to time constraints, most companies decide to perform the accelerated stability test, which normally includes keeping the samples at elevated temperatures (37, 40 or 45 degrees Celsius) over a period of three months.

CE.way also tests the stability in a refrigerator and performs a freeze-thaw test, which is usually used to predict the stability of the product during transport. If transparent packaging is used, we also test the stability of the product when exposed to sunlight.

Whichever stability test is chosen, it should consider the following:

  • It should identify the tests that will predict the effects of normal conditions of storage and use by the consumers on the product
  • It should evaluate the critical physical, chemical and microbiological properties of each product
  • Variation in process conditions
  • The impact of packaging on the contained product and the effect of the product on the packaging

CE.way offers a range of different cosmetics stability tests and we help you choose the right one, based on the type of your product and its desired shelf life. Our stability tests are conducted according to ISO 18811:2018. During the stability test, we monitor the following.

  • Various physical and chemical specifications of the product (such as pH, viscosity and density)
  • Organoleptic properties of the product
  • Microbiological specifications (Candida albicans, Pseudomonas aeruginosa, Staphylococcus aureus, mould and yeast)
  • Packaging compatibility

If you want to find out more, please check our blog on the stability and compatibility test.