1. The tingling of Spring Letter VC essence may be caused by the skin's sensitivity to some of its ingredients or the maladjustment to the first use.
2. It is recommended to reduce the usage first, gradually establish skin tolerance, or try conducting a skin test on the inner wrist to observe for any allergic reactions.
If the stinging sensation persists or worsens, it should be stopped immediately and the advice of a professional dermatologist or beauty consultant should be consulted.