Using niacinamide before retinol works well. So does combining them into one product. A 2016 study found that a product containing retinol, niacinamide, hexylresorcinol, and resveratrol improved fine lines, sallowness, wrinkling, hyperpigmentation, and skin tone.
Niacinamide and retinol can be used together with a five-minute gap between application but are likely to be just as effective if you use them at separate times of the day.
Don't Mix: Niacinamide and vitamin C. Although they're both antioxidants, vitamin C is one ingredient that's not compatible with niacinamide. "Both are very common antioxidants used in a variety of skincare products, but they should not be used one right after the other," says Dr. Marchbein.
Retinoids work best if you use them daily. Specifically, they should be used at night because some types are deactivated by light and air. It's important to start slowly and allow your skin time to adjust. Using too much too quickly can cause redness, dryness, and irritation.
Is it safe to use retinol every day? For most people, yes — once your skin is used to it, that is. That said, there are some people who may not want to use it frequently or at all.
Rouleau says the best time to use a scrub is in the morning. Overnight you've loosened up dead skin cells with your glycolic acid or retinol products, making the morning a perfect time to brush them off.
The best product you can use in conjunction with retinol, according to Dr. Zeichner, is a moisturizer, which can help hydrate skin and reduce the risk of irritation from retinol. “Some people even prefer to mix their retinol with a moisturizing cream to dilute it out,” he says.
Layering products correctly is important if you want your products to work. If you place one product on your skin, like a serum, and follow up with another product whose molecules are smaller than the first, like a toner, then the second product cannot penetrate the first layer.
Always apply Retinol products at night, as sunlight can diminish their power. If you're a prescription-strength user, use Retinol as the first layer on your skin after washing your face with a cleansing cream and before applying your anti-aging moisturizer.
Retinol should always be applied at night.
It's especially sensitive to light, which is why it's kept in dark packaging or packaging that doesn't let any light through. In order to avoid unnecessary sun damage, only ever apply retinol before you go to bed.