It's best to apply Vitamin C before Retinol, as Vitamin C has a lower pH than Retinol. Once your skin absorbs the Vitamin C serum, your skin will return to its regular pH levels after 30 minutes or so. (You want your skin to return to its normal pH levels so vitamin C doesn't lower the pH of retinol.)
Though it's perfectly fine to use vitamin C and retinol or retinoids in your skincare routine, each is better suited to a different time of day. Vitamin C is best used in the morning, while retinoids are better for your nighttime skincare routine.
You can use each every other day, or even start out using retinol every third day while your skin adjusts to it. Keep in mind, everyone's skin is different--not everyone is going to experience irritation if they use retinol and vitamin C together. It's entirely possible they won't experience any irritation at all.
It's best to apply Vitamin C before Retinol, as Vitamin C has a lower pH than Retinol. Once your skin absorbs the Vitamin C serum, your skin will return to its regular pH levels after 30 minutes or so. (You want your skin to return to its normal pH levels so vitamin C doesn't lower the pH of retinol.)
As long as you choose a vitamin C derivative that is close in pH to your retinol, then you can use them at the same time, since they will not destabilize each other. Choose formulas with one or more of these vitamin C derivatives: Ascorbyl glucoside (pH 5.0 to 7.0)
So, should I use vitamin C or retinol for wrinkles? Well, when it comes right down to it, the choice is really in what you're looking to do for your skin. While vitamin C is incredible for the skin because of its ability to help brighten and improve hyperpigmentation, the best active ingredient for wrinkles is retinol.
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.
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.
Vitamin C is used for its anti-ageing benefits as it boosts collagen, improves elasticity and repairs damaged cells. Using it before bed is safer and has far more beauty benefits and thus, we totally recommend you to use it in the night, before hitting the sack.
Vitamin C moisturizers are also becoming more common, Dr. Lamb says, and you'd want to use those at the end of your skin-care routine. And if you're wondering if you can use vitamin C every day, the answer is yes.
You'll likely want to use retinol once or twice per week initially and work up to using it more than that. The reason: Retinol can initially be drying, especially if you have sensitive skin, so it's a good idea to give your skin some time to adjust to the change in your routine.
Retinol (leave to absorb for 10-20 minutes)
Retinol is also an ingredient that should be left to absorb sufficiently into the skin before following up with another product. “It is important to leave a 10-20 minute wait time before applying the next product.
Perform the nighttime skincare routine as directed above. After applying retinol to your skin (while it's dry) allow it to sit for 10-20 minutes. Mist your face with water or a facial spray, and then apply your hyaluronic acid. (HA serums are most effective when they're applied to damp skin.)
Is it a good idea to combine Vitamin C, Retinol and Hyaluronic Acid in a skincare routine? Yes. These ingredients work well when used individually and even better when paired together.
Evening Routine
Due to how potent they are it is best to avoid using vitamin C and retinol together, but instead opt for applying vitamin C in your morning routine followed with retinol in the evening.
“AHA, BHA, retinol, and benzoyl peroxide can be mixed with moisturizing ingredients like hyaluronic acid, ceramides, and rosehip oil to get effective results — just ensure you are not using retinol as well as AHA or BHA's during the day," says Graf.