What are the signs that a product has expired?

Aqueous skincare products (creams, serums, lotions, etc.) become contaminated more quickly than anhydrous powders, especially when they are exposed to a humid environment such as bathrooms.

Even though cosmetics contain preservatives in their formula to help prevent the growth of bacteria and yeast, they can break down over time, even if unopened, particularly when stored in humid environments or exposed to direct sunlight, thus becoming real breeding grounds for potentially pathogenic organisms.

It is recommended to avoid keeping a skincare product, unopened and fully sealed, for more than three years, provided it has been properly stored in a dry and cool place.

This is why most cosmetic products display a symbol of "period after opening" (PAO) on their packaging, represented by the image of an open jar followed by a number and the letter M. This indicates the maximum number of months a product should be used after you have opened it. After this period, it is advised not to use the product even if it still appears to be fine. Although this element is important, it is only useful if you remember the month in which the product was opened. But then how do you identify if a skincare product has expired if its use-by date has not been rigorously followed or if it simply does not contain one?

Tip : To facilitate tracking the shelf life of your cosmetic products, consider noting down the date you first opened the bottle on the container itself.

Without a clear expiry date, one must then monitor for signs of degradation and contamination. Indeed, there are certain visible signs that a cosmetic product has deteriorated, but they do not always appear. In the face of these indications, it is preferable to discontinue the use of the skincare product.

• Phase Separation: Liquid products such as foundations or creams can sometimes separate, resulting in an oily layer appearing on the surface. This is often a sign that the emulsifiers are no longer functioning properly.

• Colour Change : Discolouration or a change in colour can also indicate that the ingredients have degraded. Over time, skincare products oxidise and may take on a different hue. Similarly, pigments can lose their brightness/colour.

  Although it can generally indicate that a skincare product is expired, this is not always the case. Retinol and Vitamin C, for example, can change colour when exposed to air and light, but they can still be used safely. However, they no longer function optimally, making the product less effective.

• Alteration in Consistency : A change in texture is often a sign of expiration. Indeed, a grainy or viscous texture, or a product that has now become liquid, dry or pasty compared to its usual state are indicators of deterioration. A powder that becomes difficult to use is also a sign of expiration.

  If you notice that your skincare product is dry or crumbly, adding water to moisten it is not the solution. On the contrary, this could potentially introduce bacteria.

• Unusual Odour : Another indicator is the emergence of an unpleasant, different odour. If the skincare product begins to have a rancid, alcoholic, or sharp smell, different from its original scent, it is likely expired.

• Appearance of mould: If black, green or blue spots appear, the product is expired and should be immediately discarded.

If a skincare product has been exposed to heat, direct sunlight for an extended period, or temperature fluctuations, such as a sunscreen, it is better to avoid using it even if the expiration date has not yet been reached.