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KJ Skin Journal

Three flasks of Vitamin C serum at different stages of oxidation, from fresh and clear to significantly oxidised and brown, next to a KJ Serums Triology bottle

Does Vitamin C Serum Expire? Signs of Oxidation & Why Freshness Matters

Pure Vitamin C serum can oxidise over time. Learn the visible signs, how to store it correctly, and how long a bottle stays active once opened.