What No One Told Me About Using Vitamin C In Skin Care

megan decker

Testing skin care products is an occupational hazard. In the past, I’ve been lucky. I’ve had relatively no reactions (as I used to claim). But last month, boy, was I humbled.
I’ve run out of my last serum of the morning, Major Fade Hyper Serum, by #PillowtalkDerm, which I highly recommend. I switched to a well-known brand of vitamin C serum that comes highly recommended by doctors and other editors. Also, Kaia Gerber uses a full line of products, not sponsored products. However, I ignored the label of this serum, which says: 25% L-ascorbic acid.
You might be thinking, “Be careful!”. For those who don’t know, L-ascorbic acid is the active form of the antioxidant vitamin C and is commonly found in today’s “brightening” serums. According to dermatologists, L-ascorbic acid has long been considered the most potent form of vitamin C, if not the gold standard. The problem? It is unstable and, in high concentrations, can cause irritation or inflammatory reactions.

While this particular vitamin C serum didn’t burn or sting when it came in contact with my skin, two days after using it, I woke up with a swollen right eye. Imagine that scene in Hitch where Will Smith sucks Benadryl through a straw. The swelling quickly progressed to red, dry, scaly skin around my eye and perioral dermatitis, which I self-diagnosed after Googling “white bumpy rash around the mouth.
My doctor prescribed me tapered oral prednisone. Both she and my dermatologist instructed me to stop all skincare immediately. (Note: If you have an allergic reaction to skin care products, see a medical professional immediately). I flushed out the vitamin C serum and sorted it for recycling. It was a $140 bottle of product, so the money had run out.
My swelling went down quickly. After about a week, my skin returned to baseline except for a bum spray of Tower28 SOS Daily Rescue Facial Spray with hypochlorous acid. But I had one lingering question. Why did this vitamin C serum cause such a severe reaction? And do I now have to give up topical vitamin C forever? Here’s what I’ve gathered.

allergic reaction to vitamin C serummegan decker

Mind the vitamin C concentration

I want to be clear: this inflammatory response is not the fault of this particular serum or an ingredient like vitamin C; this is a significant user error. My main mistake was, you guessed it, not reading my label. This brand-new serum comes in an airless bottle, not a glass dropper, which might expose the formula to light or air, so I’m sure instability is not an issue. It’s just that its 25% concentration is too high for my sensitive skin. According to dermatologist Dr. Sherene Idriss, who talks about vitamin C on her channel, L-ascorbic acid at concentrations below 10% is recommended for sensitive skin types.” Dr. Idriss explains, “Anything over 10 percent can irritate you.

Consider the pH scale

Although it is an antioxidant, vitamin C is acidic, especially those formulations based on L-ascorbic acid.” Dermatologist Dr. Whitney Bowe explains, “The problem with L-ascorbic acid is that it is precarious, and to remain stable, it has to be placed at a very low pH, which tends to burn and irritate sensitive skin. For context, the baseline pH of our skin is 5.5. L-ascorbic acid-based vitamin C serums typically have a pH of 3.5 or lower, which is comparable to the pH of a home chemical peel.
In hindsight, if I had understood this basic pH equation, I would have dismissed the vitamin C serum as a simple, throw-on daily serum, but more like a peeling pad that could burn my skin like a beef fillet.

Be careful of over-exfoliation

This brings me to my next question: before implementing a high concentration of active vitamin C serum, I used retinol regularly at night and exfoliated twice a week. This was fine, but the addition of the high-intensity L-ascorbic acid likely pushed my barrier into a state of reactive breakage. My colleague Jacqueline Kilikita recently reported on the issue of exfoliating acids in skin care. In the report, she talks about the dangers of layering on the often sexy exfoliating acids that promise to shine but can damage the skin barrier, especially if you are sensitive.
Again, L-ascorbic acid itself is not the problem; it’s the potential over-exfoliation. In the future, I will take a more conservative approach to any vitamin C introduction: patch test the serum before putting it on my face, always use a hydrating moisturizer, and cycle through all other exfoliating acids in my routine.

Try inactive forms of vitamin C

I’m not trying to eliminate L-ascorbic acid because it works (ask anyone who uses C E Ferulic and has lovely, glowing skin – and there are many of them). However, given that my sensitive skin reacts negatively to it, Dr. Bowe offers an alternative: “I’m very excited about the newer, more stable [vitamin] C derivatives, such as tetradecyl ascorbate.” Dr. Idris also mentioned that tetradecyl ascorbate is a good vitamin C option for sensitive skin.” It is oil soluble, while L-ascorbic acid is water soluble,” Dr. Idriss explained.” It can have a pH around 5, so it’s not too acidic, and many skin types can tolerate it.”
Although tetradecyl ascorbate is the inactive form of vitamin C – which means it must be converted to L-ascorbic acid within the skin to work – it provides the same benefits as the active form.” Dr. Idris said, “It is a skin brightener and a collagen booster and has the photoprotective antioxidant properties of pure vitamin C. By this logic, it functions in the same way as L-ascorbic acid, only gentler.

It’s okay to not use vitamin C at all

Skincare is ultimately a personal matter. This is not a slam against vitamin C. However, some dermatologists don’t like it. Dr. Anjali Mahto, a dermatology consultant, told R29, “I don’t use vitamin C in my skincare routine very often, and I can take it or leave it.” Here’s why.” I also don’t like products layering on my patients’ skin,” Dr. Mahto explains.” The more variables I put into a treatment plan, the more likely I will have peeling, irritation, and sensitivity. Dr. Mahto prefers to recommend azelaic acid over vitamin C, which also helps with hyperpigmentation and evens out skin tone.
I still use a very streamlined routine. I use a mild oil-based cleanser to remove makeup, followed by a moisturizer and sunscreen. The dreaded vitamin C reaction and the ensuing research, as a consequence more than a curiosity, made me think of Jessica DiFino’s coverage in Unpublishable magazine. She talks a lot about how our skin is a self-regulating organ and assumes that skincare products often create problems and do more harm than good, especially on a large scale in an industry. In the case of the vitamin C serum and my recently traumatized skin, I’d be better off without it.

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