A stability test checks whether a cosmetic product remains stable in terms of quality, safe and fit for purpose over a defined period of time.

During the test, the formulation and – where applicable – the packaging are stored for several weeks under various conditions (e.g. 4 °C, room temperature, 40 °C) and checked regularly. Factors assessed include appearance, odour, pH value, viscosity and any potential interactions with the packaging material.

Passing a stability test is the basis for determining the shelf life and authorising the product for production.