As a seasoned expert in the realm of clean beauty and skincare, I can assure you that using expired makeup is a practice that should be avoided at all costs. Here's why.

Every product, from your favorite lipstick to your go-to foundation, has a shelf life. This is the period during which the product maintains its integrity and efficacy. After this time, the product may not perform as expected and can even become harmful.

The primary concern with expired makeup is the growth of bacteria. Over time, bacteria can proliferate in your makeup, especially in products that come in contact with your face or eyes. This can lead to skin irritations, breakouts, and in severe cases, infections.

Another issue with expired makeup is the degradation of the product's active ingredients. As a chemical scientist, I can tell you that the molecules in your makeup begin to break down over time. This can lead to a decrease in the product's effectiveness. For example, the SPF in your foundation may not provide the same level of protection, or the pigment in your eyeshadow may not be as vibrant.

Lastly, the texture and consistency of your makeup can change over time. Lipsticks can become dry and hard, mascaras can become clumpy, and foundations can separate. These changes can make the product difficult to apply and may not give you the desired result.

In my experience, it's always best to follow the recommended shelf life of your makeup products. Not only will this ensure that your makeup performs as expected, but it will also help to keep your skin healthy and beautiful. Remember, your skin is your largest organ, and taking care of it should always be a priority.