I have reactive skin — how should I introduce a vitamin C day cream?

Vitamin C (ascorbic acid or its derivatives) is a potent antioxidant, but in leave-on products it can cause transient tingling, slight redness, or a warm sensation, especially on skin with a compromised barrier or conditions like rosacea. The source advises introducing any vitamin C face cream gradually. A practical approach: cleanse with a gentle, fragrance-free cleanser, pat dry, then apply a pea-sized amount of this cream to the forehead, cheeks, and chin — avoiding the orbital bone entirely. Use it every other morning for the first two weeks. If no irritation appears (no persistent stinging, no new rough patches, no itching), increase to daily morning use. If irritation occurs, drop back to every third day or mix a drop of the cream with a plain moisturiser to dilute the active concentration. Always follow with a dedicated sunscreen if you'll be outside longer than brief urban exposure, as vitamin C can make skin slightly more photosensitive. Discontinue use if irritation persists beyond a few minutes or if you develop an allergic reaction (swelling, hives, intense itching).