04/06/2026
If your Vitamin C serum started out clear but is now dark yellow or brown… it’s oxidized. 🍊
A fresh serum should be clear to pale straw-colored. If yours has turned a deep amber, the formula has degraded. Not only has it lost its potency, but it can actually become irritating for sensitive skin types.
If it’s brown… it’s done. Time to toss it and upgrade!