Important Question: When Will Unopened Beauty Products Expire?

Serums are often formulated with antioxidant and antiaging ingredients such as vitamin C, resveratrol, retinol, and peptides which are notoriously unstable (meaning they don't have a long shelf life). Watch out for yellowing/brown discoloration that tells you the product may be oxidized and is therefore ineffective. If you don't see any of these signs, you should be OK to use the product up to six months after the expiration date listed." — Tanzi