Hey! The Ordinary does not recommend combining this serum with C-vitamin. There are many possible reasons for this.
🌸 Soothing & Barrier serum contains many active and effective ingredients. The combination of several powerful antioxidants can cause skin irritation, especially on sensitive skin.
🌸 The pH value of the Soothing & Barrier serum is close to the skin's natural pH. In contrast, C-vitamin (L-ascorbic acid) works optimally at a lower pH. When combined, the pH discrepancy can weaken the effectiveness of C-vitamin and cause skin irritation.
If you want to use both C-vitamin and Soothing & Barrier serum, I recommend using them on different days to avoid skin irritation and to get the best benefits from both products.