How to Use Vitamin C Serum Without Irritation (Complete Guide for Sensitive Skin) To use vitamin C with less risk of irritation, choose a formula that suits your routine, test it first, introduce one new product at a time, and follow its directions. Do not keep using a serum that causes burning, persistent stinging, or … Continue reading How to Use Vitamin C Serum Without Irritation (Complete Guide for Sensitive Skin)