In just a few short weeks, many of you who pre-order FutureDerm CE Caffeic Serum will be ready to incorporate it into your routine along with FutureDerm Time-Release Retinol 0.5. But you’ve probably heard that retinoids and vitamin C shouldn’t be used together, right? They might not be optimal used at the same time but that doesn’t mean that they shouldn’t be used in the same routine.
Why Shouldn’t You Use Retinol and L-Ascorbic Acid at the Same Time?
In part, it has to do with the pH that’s best for each. The optimal pH for retinol conversion to its active form, retinoic acid, is somewhere between 5.50-6.0 (Journal of Investigative Dermatology). Retinol goes through a two step oxidation process, being converted into retinaldehyde and then all-trans retinoic acid (Journal of Investigative Dermatology). Because the enzymes that do this (dehydrogenases) work best at a neutral pH, it’s not optimal to mix them with something acidic, like alpha hydroxy acids or the form of vitamin C known as L-ascorbic acid.
On the other hand, L-ascorbic acid is not only an acid – it also needs to be formulated at an acidic pH. A study from Dermatologic Surgery shows that, in order for L-ascorbic acid to enter the skin, it has to be formulated below a pH of 3.5.
Changing to another form of vitamin C doesn’t change the fact that it needs to be formulated at a pH of 3.5 for maximal efficacy. Non-acidic derivatives of vitamin C — such as magnesium ascorbyl phosphate — typically must be converted into L-ascorbic acid in the skin (Photochemistry and Photobiology). So they also presumably need a pH below 3.5 in order to be maximally efficacious.
While this doesn’t necessarily mean that products with vitamin C and retinol won’t work when put together — in fact, researchers have found that the combination helps to reverse signs of aging (Skin Pharmacology and Physiology) — it does mean they won’t each work as well as if they were used separately. So, if you want to get the most out of your products, you shouldn’t mix vitamin C with retinol.
So How Should They Be Used?
But you can still use a retinoid with a vitamin C serum, just at different times. This is actually practical in a few ways, because the way that retinol and vitamin C work can be complementary to one another.
First, retinol is converted into all-trans retinoic acid, which can make skin photosensitive (British Journal of Dermatology). Since retinol is only 5-10% as potent as all-trans retinoic acid (Clinics in Dermatology, Journal of Investigative Dermatology), sun protection is less of a concern than with a prescription retinoid, but still necessary.
This is where vitamin C serum serves as an excellent daytime complement to retinol. The 15% vitamin C (and 2% vitamin E ) boost sunscreen protection for UVA and UVB rays when applied first topically (British Journal of Dermatology, Acta Dermato-Venereologica).
Bottom Line
We’re dedicated to giving you what’s out there research-wise, and research shows that retinoids and vitamin C are both excellent for anti-aging, but that they might not be as effective when used together. Because our FutureDerm CE Caffeic Serum is making its debut, we wanted to let you know the best way to use it is during the day, saving our FutureDerm Time-Release Retinol 0.5 for night — just to make sure your products are the most effective that they can be.