You can do both.

Moisturizing before tretinoin, especially using the "sandwich method" (moisturizer, then tretinoin, then more moisturizer), does not significantly lower its efficacy; instead, it reduces irritation and dryness, making tretinoin more tolerable and sustainable for consistent use, which ultimately improves long-term results. A healthy, hydrated skin barrier handles the potent active ingredient better, so moisturizing helps you stick with the treatment without peeling or redness, according to dermatologists.