“I exfoliate with glycolic acid. Can I follow it up with vitamin C?”
Short answer: yes, you can. But that doesn’t mean that you should…
Long answer: it’s complicated. Here’s what I mean:
What The Heck Is L-Ascorbic Acid (Vitamin C)?
L-Ascorbic Acid is the pure form of vitamin C, a powerful antioxidant that:
- Fights the free radicals that give you wrinkles
- Boosts the production of collagen, the protein that keeps skin firm
- Reduces transepidermal water loss, helping to keep skin hydrated
- Brightens skin and fades away hyperpigmentation
If you’re in your early ’20s and want to kickstart your antiaging journey, vitamin C is the perfect place to start.
The catch? L-Ascorbic Acid ain’t the only form of vitamin C. This antioxidant come in many forms. Like, Magnesium Ascorbic Phosphate and Ascorbyl Glucoside, to name a few.
For this post, I’ll cover just L-Ascorbic Acid. It’s the most pH dependent. Put simply: it works better at a pH of 3.5 or lower.
FYI, that doesn’t mean that if you raise the pH to 3.6, L-Ascorbic Acid becomes useless. It’s just the higher up you go, the less effective it gets.
Other forms of vitamin C aren’t so finicky. They work even at higher pHs. But why am I telling you this?
Because the higher pH of glycolic acid is usually cited as reason why it’s incompatible with L-Ascorbic Acid. Keep that in mind. We’ll come back to it.
- Drunk Elephant C-Firma Day Serum ($80.00/£67.00): available at Cult Beauty, Sephora and SpaceNK
- Paula’s Choice C15 Booster ($49.00): available at Feel Unique, Nordstrom and Paula’s Choice
- Skinceuticals CE Ferulic ($166.00): available at Adore Beauty, Blue Mercury and Dermstore
Related: Why You Should Add Vitamin C To Your Skincare Routine
What The Heck Is Glycolic Acid?
Glycolic acid is the best exfoliant for dry skin (if you a different skin type, you can stop reading now. You don’t need to mix glycolic acid with anything. Ha!).
A member of the Alpha Hydroxy Acids (AHAs) family, glycolic acid dissolves the glue that holds skin cells together so they can easily slough off.
Once those dead cells are off your skin, your complexion instantly looks better. Your skin is softer to the touch. Your fine lines look smoother and smaller. And your entire face glows as if lit from within.
That’s not all. Glycolic acid acts as a humectant: it attracts and binds water into the skin, helping to keep it hydrated. See why it’s so good for dry skin?
I’m sure you’ve also heard that glycolic acid can boost collagen. That’s true – but only at 10%+ concentrations. Most topical skincare products don’t have that much. 🙁
- Drunk Elephant T.L.C. Framboos Glycolic Night Serum ($90.00): available at Cult Beauty, Sephora and SpaceNK
- Paula’s Choice Resist Daily Smoothing Treatment with 5% AHA ($33.00): available at Dermstore, Look Fantastic, Paula’s Choice and Selfridges
- The Ordinary Glycolic Acid 7% Toning Solution (£6.80): available at Beauty Bay and Cult Beauty
Related: The Complete Guide To Glycolic Acid: What It Is, What It Does & How To Use It
Why You Can Use L-Ascorbic Acid (Vitamin C) And Glycolic Acid Together
Remember when I told you that critics say you can’t mix vitamin C with glycolic acid because they work at different pHs? That’s not exactly true.
As you know, L-Ascorbic Acid works best at a pH of 3.5 or lower. Some glycolic acid exfoliants on the market go above that. You can find some with a pH as high as… 4!
Not much of a difference, is there? Truth is, pure vitamin C and glycolic acid work well at around the same pH.
They both like it low. But if you go too low, you can literally burn your skin! That’s why you’ll never find a skincare product with a pH of 2.
As long as difference between pHs is so little, you’ve got nothing to worry about. Both glycolic acid and vitamin C will work at their best.
Sue Ann Wee, a dermatologist at the Schweiger Dermatology Group in New York City, agrees: “From a general chemistry compatibility point of view, vitamin C (l-ascorbic acid) can be combined in cosmetic formulations with hydroxy acids, such as glycolic acid, since both can maintain their efficacy in similar acidic pH ranges.”
Why You Shouldn’t Use L-Ascorbic Acid (Vitamin C) And Glycolic Acid Together
You won’t compromise the effectiveness of L-Ascorbic Acid or glycolic acid if you use them together. But the mixture can be too harsh for your skin.
Here’s the deal: both L-Ascorbic Acid and glycolic acid are powerful. In skincare, powerful often means irritating.
Used alone, they can sting and irritate skin. Used together, you’re doubling the risk of irritation.
If you have resistant skin that can tolerate anything, then yes, you CAN use L-Ascorbic Acid and glycolic acid together. Exfoliate and then layer vitamin C on top.
But if you have sensitive skin or are using these actives for the first time, don’t risk it. You can minimise the risk of irritation by using them at different times of the day.
That’s what I do. And my skin is pretty resistant. I just don’t believe in overdoing skincare. Too much of a good thing can backfire. 😉
I like to apply L-Ascorbic Acid in the morning because studies show that it can boost the sun protection of your sunscreen. I then use glycolic acid every other night.
This way, I get the best of both worlds without the irritation. 🙂
The Bottom Line
You can totally use L-Ascorbic Acid (vitamin C) and glycolic acid together without making them ineffective. But that doesn’t mean it’s a good idea. For some people, this combo is too harsh. If that’s you, use them at different times of the day.