What are the signs that a product has expired?

Aqueous skincare products (creams, serums, lotions, etc.) become contaminated more quickly than powders (anhydrous), especially when they are exposed to a humid environment like 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 completely sealed, for more than three years, provided it has been properly stored in a dry and cool place.

That's why most cosmetic products display on their packaging a symbol for "period after opening" (PAO), 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 recommended 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 expiration 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 the date you first opened the bottle on the container itself.

Without a clear expiration date, one must 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.

• Color Change : Discoloration or a color change can also indicate that the ingredients have degraded. Over time, skincare products oxidize and may take on a different hue. Similarly, pigments can lose their brightness/color.

  While it is generally assumed that a change in a skincare product's color indicates it has expired, this is not always the case. Retinol and Vitamin C, for example, can change color when exposed to air and light, but they can still be safely used. However, they no longer function at their peak, making the product less effective.

• Alteration in Consistency : A different texture is often a sign of expiration. Indeed, a grainy, viscous texture, or a treatment that is now liquid, dry, or pasty than usual 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 Odor : Another indicator is the emergence of an unpleasant, different odor. If the skincare product begins to have a rancid, alcoholic, or sharp smell, or smells different from its original scent, it is likely expired.

• Appearance of mold: 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.

Continuing to use and apply expired skincare products can have adverse effects on the skin (irritation, rash, itching, redness, eye infection, warming sensation, etc.). Over time, opened skincare products can deteriorate and become breeding grounds for microorganisms. The use of expired cosmetic products can cause various adverse effects on the skin due to the degradation of active ingredients, bacterial or fungal contamination, or changes in the product's chemical composition over time.

A study (n = 55 samples) revealed that expired cosmetics have a higher level of microbiological contamination than those before the expiration date. Potentially pathogenic microorganisms, such as Staphylococcus spp, Aspergillus spp and Penicillium spp, were found in relatively high quantities in most of the expired cosmetic samples, being associated with a high risk of triggering allergic and infectious reactions.

Similarly, another study evaluated the makeup habits of 44 female students. According to the results, 31 out of 44 participants (70.5%) owned a makeup product that had been expired for over a year (34.1%), 6 months (13.6%), or 3 months (13.6%), primarily eye makeup (mascara, eyeliner, eyeshadow). Among 40 collected and still used mascaras, 67% were contaminated, with 79% of the samples containing the bacteria Staphylococcus aureus and 13% containing the fungus Pseudomonas aeruginosa. However, using expired products can jeopardize skin health and cause various discomforts. Indeed, expired skincare products can compromise the skin barrier and disrupt the skin's microbiome.

• HAAS S. E. & et al. Research on the use of expired makeup and microbiological contamination of mascaras. International Journal of Cosmetic Science (2013).

• GOSPODAREK-KOMKOWSKA E. & al. Microbiological Purity Evaluation of Cosmetics Used by Single and Multiple Individuals and Cosmetics Post-Expiration Date. Annals of the National Institute of Hygiene (2017).