3 min read
Ask Jenna is a monthly advice column from Bazaar’s beauty director, Jenna Rosenstein. Got a pressing question about fitness that you want to see addressed? Don’t hesitate to reach out and message Jenna on Instagram.
Dear Jenna,
I use a vitamin C serum every morning, and it’s turned brown—it’s not even old! It also smells weird, though it always smelled weird. Is this serum even doing anything? How do I know if it’s gone bad?
Vitamin C serums are known for their brightening effects, but they also come with a few challenges. If your serum has turned brown and has an odd smell, you might be wondering if it’s still effective. It’s a common concern, as many vitamin C products have been known to deteriorate over time.
I consulted with cosmetic chemist and science educator, Michelle Wong, who has conducted experiments to determine the stability of vitamin C in its various forms. According to Wong, L-ascorbic acid—the most potent form of vitamin C—is highly sensitive to factors like temperature, air, and light exposure.
One indicator that your serum is no longer good is an unusual smell. Wong explains that the breakdown of vitamin C leads to various reactions that can alter its scent. If you detect any significant changes in odor, it’s a sign to consider replacing it.
Next, let’s discuss color. Wong ran a test keeping one bottle of serum in the fridge, another at room temperature, and the last in direct sunlight. The results revealed that exposure to sunlight leads to a deeper brown color. The room temperature serum also darkened, though less dramatically. The one kept in the fridge retained its original pale hue, indicating that cooler temperatures help maintain its effectiveness. However, color changes generally mean reduced efficacy even if some benefits may still exist.
Wong emphasizes checking the expiration date on your serum and suggests adhering to it, as brand testing ensures product stability. Also, consider the packaging—dark glass bottles offer better light protection, while airless pumps help limit oxidation. But keep in mind, not all products marketed as “airless” are entirely devoid of air exposure. Even tiny gaps can allow oxygen to interact with your serum.
For the most effective use of your vitamin C serum, Wong advises regular application and purchasing only as much as you can realistically use. Avoid being swayed by the influx of new products on social media; sticking to a routine can help you maximize the benefits of your skincare regimen.
Conclusion
Understanding the stability of active ingredients in your skincare products, like vitamin C, can significantly enhance their effectiveness. Monitoring changes in smell and color can help you assess their validity, ensuring you get the most out of your skincare routine. Remember, consistency in use and mindful purchasing can lead to better results over time. Always refer to expiration dates and prioritize products that best suit your skincare needs for maximum benefit.
