The expired stock solution cannot be used. According to the inquiry data, Yanzhengtang stock solution is an efficient skin care product, which can quickly replenish nutrition and moisture to the skin in a short time and make the skin glow bright and healthy again. After the expiration date, the original lotion can no longer be used, the nutrients have been destroyed, and the original efficacy has been lost, so it can not maintain and care the skin and fight against skin damage.