Why is my All-In serum turning yellow/brown?

All-In Viitamin C + Lactic serum contains ascorbic acid (the most active form of Vitamin C) which can oxidize over time and with exposure to light and air. We do everything we can to keep the ascorbic acid stable for as long as possible by formulating it at a lower pH and packaging it in an opaque airless pump bottle. 

Your All-In serum should be shelf stable for up to 4 months. If you're not going to use your serum right away it can be stored in the freezer and defrosted when ready to use. Your serum is still usable and 80-90% effective if it turns light to medium yellow. If it turns dark yellow, orange or brown it's time to discard and get a fresh bottle.

You might also see some oxidizing around the opening of the pump nozzle. This is normal oxidization when ascorbic acid is exposed to air. Simply wipe it away with a damp tissue or cloth.