It's well-known that cosmetics have expiration dates, and using them beyond their shelf life can harm the skin.

However, the expiration dates for opened and unopened cosmetics are not the same! Are you unknowingly using expired cosmetics?

Expired cosmetics pose significant risks. The shelf life of cosmetics is divided into opened and unopened categories. When people commonly refer to cosmetics having a shelf life of three to five years, it's typically under the assumption that the product remains unopened. Once opened, factors such as frequency of use, storage methods, and environmental temperature can all influence the shelf life of cosmetics.

Cosmetics, including soaps and shampoos, contain added nutrients. They are not just simple cleansing products; the nutrients can breed microorganisms. Manufacturers add limited doses of synthetic chemical preservatives to inhibit microbial growth.

If cosmetics exceed their shelf life, the effectiveness of the preservatives gradually diminishes. The uncontrolled growth of pathogenic microorganisms can harm the skin, leading to acne, skin infections, and more severe consequences for sensitive skin.

Regarding efficacy, cosmetics often contain bioactive ingredients. Prolonged exposure to air, high temperatures, and sunlight can cause chemical changes, producing by-products, or causing the evaporation of active ingredients. From a comfort standpoint, if the hydration and adhesion properties change when applied to the skin, the effectiveness of the cosmetics significantly decreases or is lost.

So, what are the shelf lives of opened cosmetics and skincare products? Generally, it's indicated on the packaging with a symbol of an opened jar, and there might be "6M" or "12M" indicating 6 or 12 months after opening as the best usage period. After this time, it's not recommended to continue using them.

How to identify if cosmetics have expired? Here are some methods:

1. Based on Sensation: The properties of most cosmetics are typically very gentle, causing no discomfort when applied to the face. However, once they exceed their shelf life, cosmetics undergo significant changes in their properties. At this point, applying these cosmetics to the face can result in noticeable stinging sensations. If such sensations are experienced, even if they are very mild, it's imperative to immediately cease usage to prevent significant damage to the skin.

2. Based on Color Changes: Most cosmetics contain ingredients with vitamins, which provide moisturizing effects. When we first use cosmetics, it's essential to observe their color. This is because once cosmetics expire, they can undergo color changes, most commonly turning brown. If a significant color difference is noticed compared to when the product was first purchased, it's crucial to immediately discontinue use.

3. Based on Odor Changes: Typically, cosmetics have a mild scent without any discomfort. If a cosmetic expires, its properties change, and its original structure and scent are altered. Each cosmetic product has a unique scent, which can change noticeably if the product has expired. If you notice a change in odor or a strong, unpleasant smell, it indicates that it has expired.

Understanding the importance of shelf life is crucial when choosing and using cosmetics. By using the methods above, you can effectively determine if cosmetics have expired. Protecting your skin's health starts with choosing suitable cosmetics, allowing you to show your most confident and beautiful self.