It is a truth universally acknowledged that I’m lazy as hell. Well, not lazy precisely, but resistant to adding more work to my day that’s not absolutely necessary. Lazy. So when I recommend thinking about adding a longass, annoying step to your skincare routine, it’s only because I’ve done a lot of testing and I’ve seen major results.
In the case of C20 and C21.5 vitamin c serum, it’s been more than six months of testing. Why six months? Because this stuff is so annoying to use that I just kept it in my refrigerator for a while after first cracking into it. Before accepting my latest bottle of C21.5 from Wishtrend for the purpose of testing and review here on fan-b, I had already gone through one bottle each of C20 and C21.5, all the while wavering on whether I really wanted in on the vitamin c serum life.
By the time I accepted the review bottle of C21.5 I was sure that my skin can’t function well without some sort of vitamin c serum. I need it so much that I have installed a mini fridge in my bedroom alongside my skincare and makeup work desk so that I can more easily grab my bottle and use it consistently in my routine.
Reasons vitamin c serum is annoying
1. You really need to refrigerate it and keep it away from light or else it will oxidize. And it will still oxidize. This stuff will oxidize faster than Wishtrend can send you a new bottle if you’re not careful. It’s stupidly unstable and unless you’re careful you’ll have worthless orange-colored stuff before you’re done with the bottle.
2. Based on my understanding, you shouldn’t use this at the same time you use a retinoid–that includes prescription tretinoin (which often shows up in Pocketderm prescriptions) and over-the-counter retinol treatments. You need to keep them at different ends of your routine. I use Pocketderm at night and vitamin c in the morning.
3. For this to really work properly, you should use a pH-adjusting toner first (pH level of 5.5 or lower)…unless you’ve had a good, long waiting period after washing your face, which would allow your skin to naturally return to its acidic state. How long? Well, it seems like this would depend on the pH of one’s cleanser and the natural pH of your skin. I hate thinking about this stuff, so I just use the damn pH adjusting toner even when I have time to wait. I also suspect that my basicness carries over into my skin pH, so there’s that, too.
4. You need to give this some time to work before washing it off or slapping other stuff on top of it. I give mine at least 15 minutes. That’s 15 damn minutes of waiting for something to work in the morning before work, all the while avoiding the tempting bright sunshine of the window near the desk in my office for fear the light will turn my serum into worthless water or something. Total drag. That said, my kitten loves it–he uses that time to crawl on me and receive pets.
5. You really need to use sunscreen religiously when using a product like this. PLEASE. If you don’t plan to wear sunscreen regularly when using this product please boop de boop on out or just read this review for “fun.” Your babyish skin will desperately need coverage when using this.
6. These serums are sticky. Well, the C20 is sticky and the C21.5 is less so. I think that it would be fine to continue with one’s remaining skincare routine after using C21.5 but probably not C20–it’s just too gross. All that said, I slather so much of this stuff on that if I don’t rinse it off with water at my sink or spray my face liberally with a mist and wipe it off my makeup and skincare gets GRITTY by the end of the day. Absolutely disgusting. So either use less serum or rinse.
7. C21.5 is about as viscous as water, making it hard-ish to apply.
Just to be clear, I get my pH and vitamin c science info from reading Skin & Tonics and Snow White and the Asian Pear. Any mistakes are mine, but this is SO not the stuff that interests me about skincare. Well, I do find skincare science interesting, but it’s not the stuff I want to be researching when I should be sleeping–my interests point in other directions, so I really appreciate their approach and explanations.
In short, this stuff is super annoying to use and I hate that I love it. So why bother?
Reasons vitamin c serum is amazing
1. The brightening effects are incredible. Holy hell. Now, let’s clear something up–brightening isn’t skin bleaching. It’s just sort of rolling back one’s skin to the color underneath due to exfoliation, not changing your natural tone. I think that the best way to describe it is like cleaning by a painting restoration expert for your skin. Here’s a Mona Lisa example:
These are two different versions of the Mona Lisa (one in the Louvre by Leonardo and one in the Prado, likely painted by Leonardo’s assistant at the same time), but you get the point. All of that glowing, youthful skin was in the Prado painting already–no restorer worth jack would ever bleach the skin of even a copy of the Mona Lisa–and it was simply covered due to buildup of environmental stuff. That’s what vitamin c does: it removes the changes to your skin that happened due to the environment such as a tan due to sun exposure and reveals fresher skin below that hasn’t yet been exposed as much to the sun and other things that cause dullness (this is why religious sunscreen use is essential when using exfoliants–otherwise all that delicate new baby skin is going to get horribly jacked up, which could cause lasting skin damage). My skin is brighter than ever since I added vitamin c serum to my routine.
2. Vitamin c can help even your skin tone and reduce the appearance of skin discoloration. That means that those hyperpigmented red and brown marks left over from old acne may be able to go away faster thanks to vitamin c. I’ve certainly noticed spots fading WAY faster, which is great because I have so many. #crying
3. Anti-oxidant anti-aging something or another. Vitamin c apparently does some anti-aging sun reversal witchcraft magic that I don’t understand at all. Honestly, my approach to anti aging is just to wear sunscreen and do nice, mainly gentle things for my skin.
I realized at a certain point that non-alcoholic full professors have some of the nicest skin for people of their age group. Hence I tried to become one lol (the academic game has changed since their youth, sadly). I did the math–full professors are a bunch of people who hang out in archives all summer, have time for self-care (I’m talking about the older generation ahaha), and don’t have many reasons to make frowny faces. That’s my goal: avoid the sun and do work that leaves my face unpinched. Self-care may not be in the cards for my generation, but two out of three isn’t bad. Anyway, if vitamin c serum adds something good to the mix, great.
I vaguely remember something about antioxidants harming cells like free radicals do if there are too many of them and not enough free radicals to bond with. There’s no perfect recipe for antiaging and the research changes all the time. I’m going to use my sunscreen, use products that work well, try to live a happy, unfrowny life, and make peace with the eventual reality of aging/death. Thankfully it’s not my job to be pretty or to look young, so I’m going to focus on what I want right now and that’s untroubled skin. Side trip over, back to the main road.
How I use this serum
Once I determined that the vitamin c life was for me, I had to sort out the front end of my routine, which is where pH-dependent things like vitamin c serum and acids belong.
I start with a low-pH cleanser. Ideally the cleanser should have a pH level of 5.5 or lower when mixed with water, but damn that shit is annoying to deal with given the reality of the kbeauty cleanser selection (most have higher pH levels). LJH Tea Tree 30 Cleansing Foam is in the photo and it has a pH of about 6.5 when mixed with water. Whatever, good enough for now sigh.
Next I apply a low-pH toner. The Be the Skin Botanical Pore Toner has a pH of about 4.5, so it’s perfect for bringing my skin down to the doorstep of exfoliation level (4.0 and lower is where exfoliation occurs). Any toner with a pH between 5.5 and 4.0 would be fine in this step; I use the Be the Skin because it’s right in the sweet spot, smells good, and I already owned it woo! I allow the toner to dry for about a minute. [mega thanks to Cat at Snow White and the Asian Pear for explaining pH-adjusting toners to me–check out this post for more on pH levels and product order]
Then I add several full droppers of vitamin c serum directly to my face–I literally drop the serum onto my face. That’s a bit tricky with the liquidy C21.5, but I work fast. Why so much? I figure that I want to make sure that my whole face gets coated and feel like I shouldn’t hold back because this stuff oxidizes so fast–there’s no point in skimping on the special sauce since it’s going to go orange and worthless quickly anyway. I allow the serum to sit on my face for at least 15 minutes, meanwhile avoiding light.
Finally I either rinse my face in the sink or mist my face with a bunch of water mist and wipe off the water, depending on whether I want to run into the bathroom or not. Then I pick up with my first essence and carry on with my routine. For my whole routine from a few months ago check out this post.
The Great Purge: About pH levels, vitamin c, and purging
Here’s the deal: if you have very troubled skin like me, these serums will probably cause purging. Imagine: lots of clogs and plugs and issues all racing to the surface faster than ever before, all exploding at the same time.
In my skin this mimicked a single mega cyst except it really wasn’t. My jawline and cheeks are so clogged and troubled despite a lot of improvement that the rapid exfoliation caused by the pH-adjusting toner with the very low pH vitamin c serum seem to have caused a ton of minor clogs to purge all at once. Each of those clogs creates inflammation and irritates its neighbors and the whole thing swells into something quite horrifying, but instead of one super infected source of all trouble like a volcano, there was something like a giant hill with lots of snakeholes leading into it, each of the snakeholes leading to its own infected clog. This mean that each hill had the appearance of multiple tiny whiteheads, consistent with purging, but happening to live on the same furious hill due to proximity and inflammation.
I suspect that the reason my skin had this response is because 1) my skin is still very clogged despite lots of work and 2) my control of the pH of my skin before applying the serum means that it exfoliates in a very swift way. Many other reviewers don’t mention using a pH-adjusting toner before the serum and some talk about mixing it with other products to control the stinging–that would limit the speed at which the serum rips into one’s skin drastically.
I’ve seen lots of people mention on the Asian Beauty subreddit that they’re experiencing cystic acne as a result of starting C20 or C21.5 vitamin c serum. I’m thinking that many of these people could be experiencing a purging snakehole hill like I had, particularly if they started the serum with a lot of clogged pores. I only saw those massive blemish “hills” in places where I knew I had tons of stored clogs, which is how I knew that it was purging.
My purging was so bad that on a work trip to Boston my jawline was actually painful until I lanced the tiny whiteheads (which I knew were purging-related because the heads were small and not spread like one of my normal blemishes–it was as if I’d caught the blemish before it had been allowed to expand), allowed the nasty liquid inside to drain, and applied a Cosrx Master Patch overnight. I would actually wake up, wash my face, and use just my fingers to gently roll layers of dead skin off my jaw where the blemishes had been, which left behind these open “snakeholes” leading down to former clogs. This was amazing and horrifying/painful/annoying.
After a few weeks my skin stopped producing those purge hills and it’s now much calmer than before I started the vitamin c serum.
This whole experience really suggests that I was exfoliating too fast at first and that my skin needed a less aggressive approach. If you have troubled skin, consider starting slow so that you don’t overexfoliate and end up with a furious purge hill. You could try to use the vitamin c serum every other day or every three days–just monitor the condition of your skin and pull back if the purging gets too wild. Have plenty of acne patches on hand for when things do flare up, yikes.
C20 vs. C21.5
C20 ingredients: Water, Ascorbic Acid, Ethanol, Sodium Lactate, Butylene Glycol, Glucose, Camellia Sinensis Leaf Extract, Rosa Davurica Bud Extract, Carthamus Tinctorius (Safflower) Flower Extract, PEG-60 Hydrogenated Castor Oil Sodium Hyaluronate, Bis-PEG-18 Methyl Ether Dimethyl Silane, Diethoxyethyl Succinate, Ammonium Acryloyldimethyltaurate/VP Copolymer, Xanthan, PEG-180, Gluconolactone, Beta-Glucan, Citrus Aurantium Dulcis (Orange) Oil,Zinc PCA, Panthenol, Niacinamide, Glycerin, Tocopheryl Acetate, Lecithin, Caprylic/Capric Triglyceride, Ubiquinone, Diisopropyl Adipate, Phenoxyethanol, Methylparaben. CosDNA analysis.
C21.5 ingredients: Hippophae Rhamnoides Water (70%), Ascorbic Acid (21.5%), Sodium Lactate, 1,2-Hexanediol, Sodium Hyaluronate, Panthenol, Cassia Obtusifolia Seed Extract, Allantoin, Xanthan Gum, Ethyl Hexanediol. CosDNA analysis.
Ingredient comparison: C21.5 obviously pares down the ingredient list of the original, ditching simple alcohol (ethanol) that can be drying, a few essential oils that can be irritating, and niacinamide that can put a damper on the effectiveness of vitamin c, it seems. Gone is regular water, replaced by hippophae rhamnoides (sea buckthorn) water, a pretty major upgrade–it also appears in LJH’s tea tree 90 essence. Overall, the C21.5 list seems like it was designed to appeal to people worried about chemicals and parabens. Eh, ok.
For my skin and routine, there were two things noticeably better about the C21.5 serum: less stinging and gentler purging. I found that the C20 serum stung my skin a bit more and seemed to rip into my blemishes with greater ferocity, possibly due to the simple alcohol in the C20 formula causing a bit more drying. For me, that’s a good reason to order the C21.5.
That said, if I were very low on money the next time I needed vitamin c serum or if C21.5 sold out for a bit, I wouldn’t be too stressed since I could easily get by with C20 without much stress especially since it costs less and I can order it on Amazon with Prime shipping and it’s still cheaper than C21.5.
I think that the choice between the two comes down to money, really: are you willing to pay a bit more for a gentler formula (that your skin may not even really need)?
A roundup of reviews
I really really recommend reading a lot of reviews about this product before taking the plunge. If you’re interested in the science side of things, I think that you CERTAINLY need to read some other reviews that have a better explanation of the science side of things than mine since I obviously don’t specialize in that. Here is a list of the reviews I read before taking the leap:
35th of May – this review of C20 has lots of before and after photos and finally convinced me to buy it
The Beauty Wolf – this review’s account of the C20 serum’s scar healing and blackhead removing power first put it on my radar
The Wanderlust Project – this review was frank about the stinging of the C20 serum, but also its brightening effects and ability to make one look well-rested even when that’s not the case
Skin & Tonics – this C20 review has scientific analysis, before & after shots, and a detailed rating–go there to get your science fix
Hello Pretty Bird – this comparison of C20 with Paula’s Choice Resist C15 convinced me that it made sense to go with C20 for my vitamin c due to vast price differences
The Wanderlust Project – this review of C21.5 confirmed that it works just as well as C20, but it has fewer ingredients and it’s less sticky, which convinced me to buy the C21.5 before my C20 even reached me
Berries in the Snow – this review of C21.5 casts doubt on the need for an upgrade and ultimately suggests that the cheaper C20 may be a better choice for those without sensitive skin
Critiques of C20/C21.5 that suggest you should branch out and try other vitamin c serums
Holy Snails – this analysis of C20 and C21.5 from an ingredient perspective suggests that they’re just not great formulations and some changes would allow them to be more stable; gives suggestions for Western alternatives
ratzillacosme – this review of C20 also points out that the ingredients aren’t stabilized, leading to early oxidation; gives suggestions for a Western and a Japanese alternative
My current take
I was actually inspired to write this review due to questions I receive on Instagram about which formula is better and due to a current Wishtrend deal that I ran to snatch up this morning (a bottle of C21.5, three of the new C20 sheet masks, and free shipping for the usual cost of just a bottle of C21.5 with free shipping). I go through this stuff pretty quickly and now seemed like exactly the right moment for me to re-up my supply.
That said, the critiques are on point: this product should be better–it seems to be the Lana Del Ray of skincare products: born to die. I’m wedded more to the concept of having a good vitamin c serum in my routine than having C20 or C21.5 in my routine, so I expect that I’ll branch out in the coming months and see what Japan and the U.S. have to offer at similar prices.
Where to buy it
Disclosure: This post contains affiliate links. Clicking those links before you shop means that fan-b receives a small commission, which helps to support the blog. Please see my full disclosure for more information.