To safely add Vitamin C, use it in your morning routine on clean, dry skin, followed by moisturizer and sunscreen. Keep your adapalene/benzoyl peroxide gel strictly for nighttime use, as benzoyl peroxide can deactivate Vitamin C and cause irritation if applied together. Your depigmenting cream can be used in the evening, either layered after your acne gel once tolerated, or on alternate nights. Introduce the Vitamin C serum graduallystarting two to three times a weekand always perform a patch test first. This routine maximizes efficacy while protecting your skin barrier.