I set out writing this post with one simple goal in mind: Identify objective criteria that help cut through the hype so I can find the best vitamin c serum on the market based on scientifically proven formulae, aggregate reviews, and brand reputability. Over 100 hours of research and 67 reviews later, I narrowed down a lot of options into a much smaller pool of easy to compare finalists. 

It almost goes without saying that the best vitamin C serum is the one that works of your skin, budget and value system. As such, in my search for the best serum overall, I found what is objectively the best serum for most people with normal skin, but I also found the best serums for those committed to natural and cruelty free beauty, and for those with sensitivities to common irritants like silicone, oil, alcohol and fragrance. 

If you just want the quick answer without a lot of reading scroll right down past the table of contents and you'll find the best vitamin C serum overall in the first paragraph, with the remaining categories following thereafter. The TOC navigation isn't quite right so the best way to find something is to control F. 

After the ratings there's a section on vitamin C serum benefits that gives you all the information and evidence you need to get context for my ranking criteria and also to make the most informed decision for your needs and budget. 

If you want to see all the data I compiled check out 67 Vitamin C Serum Reviews To Help You Choose.

The Best Vitamin C Serum by Budget & Needs

The Best Vitamin C Serum Overall

The Analysis

best vitamin c serum comparison table

To find the best vitamin C serum overall I ranked 67 different serums using a points system based on formulation, aggregate reviews, and brand reputability. The highest points were given to products containing the clinically proven combination of ascorbic acid, vitamin E and ferulic that also had good reviews and either an established brand or cult favourite status.

Only 7 products of the 67 had the right formula. Both SkinCeuticals and C-Firma had the highest scores, but C-Firma won simply because it costs less for the same active ingredients and is comparable as far as user experience goes. It's also cruelty free while SkinCeuticals is not. 

Drunk Elephant C-Firma Day Serum​

drunk elephant c firms best vitamin c serum

By all accounts SkinCeuticals is a great product. I've never read a bad review or heard of anyone cheesed by paying so much for something that didn't deliver. The general consensus always seems to be Yes, it's a great product, but there are others that are cheaper with the same actives. Still, I wanted to know if that was really true by analyzing the formulations and figuring out what if anything is substantially different.

best vitamin c serum top serums compared

As you can see, both C-Firma and Skinceuticals have ascorbic acid, ferulic acid and vitamin E in common, as is expected. The big difference is obviously that C-Firma has way more ingredients, which push the ferulic and vitamin E further down the ingredients list, which of course means they're less concentrated. 

I don't know whether the rest of the ingredients in C-Firma are clinically proven to be effective the way ascorbic, vitamin E and ferulic are. With a very quick search I found the following:

  • Vitis vinifera extract: This in vitro study found it had antioxidant properties and offered protection against DNA damage in cultured cells. The bioavailability and topical properties remain to be seen.
  • Sclerocarya birrea seed oil (marula oil): This in vitro study found that extracts of the marula plant have natural antioxidant properties as well as "significant antibacterial and anti fungal potential." Not sure if this extends to the oil. Again, bioavailability is uncertain.

That's just two of the additional ingredients but it's enough to convince me that 1) there isn't significant clinical evidence and 2) that doesn't mean it doesn't work and if it does it's a bonus...so why not?

Who Is This For​

C-Firma is best suited as an upgrade for an experienced vitamin C user who has used ascorbic acid before and hasn't experienced irritation.

If you've used SkinCeuticals and love it but don't love the price, C-Firma is a good step down option with the same benefits.

C-Firma is also:

  • Cruelty Free
  • Alcohol Free
  • Formulated to be free of toxic ingredients or irritants, so it may qualify as natural to some. 
  • Silicone free
  • Natural & synthetic fragrance free

Runner Up: Cellex-C

cellex c advanced c serum

Cellex-C Advanced Serum | Formulated without any of the most common irritants including silicone, fragrance of any kind, alcohol of any kind, and oil.

Although Cellex-C didn't get top marks because it's missing the strongly supported combination of ascorbic acid, vitamin E and ferulic, what it does have are tyrosine and zinc, a combination supported by this 3 month clinical trial that actually used Cellex-C. Of the 66 other serums I reviewed, none were specifically mentioned in a study.

I wasn't really planning on including runners up but I found the evidence on Cellex-C compelling enough to include it. Overall it's also quite pricey and there's still more support for the ferulic/vitamin E approach, but if you have sensitivities or just want to try something else the Cellex-C formula might be just as good. 

When To Check Out Alternatives​

C-Firma does contain oil (marula oil) so it may be irritating to those sensitive to oil. It also may contain fatty alcohol but I'm not entirely sure whether Laureth-23 is a fatty alcohol. Will update as soon as I find out.

C-Firma also contains hydrolyzed wheat protein​, which I've read can be sensitizing and cause allergic reactions on contact. It's probably more likely if you have gluten sensitivity or celiac.

Other good oil free alternatives to C-Firma are:

  • SkinCeuticals C E Ferulic on the much higher end. Linking here to the PRO size as it's the only one I could find but it a larger format is not recommended as it could oxidize sooner if it isn't used in time. Just FYI.
  • Timeless Skincare C Serum on the much lower end.
  • Cellex-C Advanced C Serum and NuFountain C20+ are also good options as neither is formulated with any of the most common irritants. Neither has vitamin E, which may be a good or bad thing depending on your skin. NuFountain has ferulic but Cellex C doesn't, so they are likely less potent than any of the options with both vitamin E and ferulic, but again it really depends on your skin. 

The Best Vitamin C Serum Entry Level

This one is easy. Timeless Skincare Vitamin C + E + Ferulic is the winner, no contest and no analysis necessary. 

the best vitamin c serum entry level

At less than $20 an ounce it's 1/10th the price of SkinCeuticals with the same active ingredients. Granted, the purity may not be the same at this price, which is of course the reason for big price differential, but this is still a great entry level c serum that also delivers on being cruelty free and free of common irritants. 

Who Is This For

Really anyone but definitely beginners. If you don't use actives, this is going to make a big difference. I'm about 3/4 of the way through my first bottle used twice daily and can confirm real results - so much so in fact that it got my husband using it too. Plus, if you're one of the unlucky few who react to ascorbic acid, this won't be a big investment to find out.

If you do use actives but want to try something else it still isn't a very big investment. I'm not sure how it would compare to the likes of C-Firma or SkinCeuticals but from my own experience with Cosmetic Skin Solutions, it isn't quite as potent. I don't know why that is but I suspect it has something to do with the purity of ingredients, which can vary greatly.

In any case it's still major bang for your buck if you go from nothing to this. 

The Best Value Vitamin C Serum

I think a lot of us (myself included) probably fall into the category of wanting to upgrade a bit but maybe not quite ready for the $80-$100 plus a bottle SkinCeuticals or C-Firma level. This analysis is done with you (and me) in mind.

Since C-Firma won best overall in my ranking I just ordered a bottle to try after my Timeless serum is finished, but honestly if I don't have to pay that much I'd prefer not to. Value is the name of the game. The best value serum is the one that balances results with cost effectiveness. 

Tie: Paula's Choice C15 Superbooster & Cosmetic Skin Solutions C + E Advanced Formula

** Note that this is Cosmetic Skin Solutions C + E Advanced Formula, not Cosmetic Skin Solutions 20% + Ferulic. The 20% formula doesn't have vitamin E, so it doesn't meet the gold standard. 

A lot of analysis had to go into this one. Probably more than any others (so far!) It's a strong tie and there's really nothing to break it. 

The Analysis

In order to find the best value serum I referred back to my analysis for best serum overall (at the very top of the page.)

The finalists in that category were chosen because they had the gold standard formula of ascorbic acid, vitamin E and ferulic acid. As far as vitamin C serums go I think the best value is where you can get that gold standard for less. Luckily, two of the finalists meet that criteria: Paula's Choice C15 Superbooster and Cosmetic Skin Solutions CE + Ferulic.

the best vitamin c serum comparison of paulas choice c15 super booster vs cosmetic skin solutions ce + ferulic

These two products seems to have more in common than not. They both have similar packaging (opaque bottle with dropper), the same rating, very similar price, and neither has any common irritants except the Paula's Choice, which has hydrolyzed castor oil. If you are at all sensitive to oil, then this is your tie breaker. If not, its a little more complicated. The price difference is nominal (around $5) so it probably isn't enough at this price point to sway anything. In order to really figure out the differences, I looked closely at the formulas. 

​In the case of Paula's Choice, there is some concern with limited data regarding sodium metabisulphite and of course potential irritation from the hydrolyzed castor oil. Otherwise no concern. The acetyl octapeptide-3 (aka SNAP 8) is a peptide complex that is an active in it's own right, but I couldn't immediately find any clinical data to back that up. 

On the other hand, as far as Cosmetic Skin Solutions goes there is some moderate concern regarding the propylene glycol and laureth-23. Otherwise, there's some clinical evidence that zinc sulfate may have beneficial effects on acne. 

I've only tried Cosmetic Skin Solutions so I can't weigh in (yet) but I did notice that CSS was much more potent on acne for me than Timeless, which doesn't have zinc sulfate. ​

​With such similar formulas and nothing to break the tie, I looked at reviews. I found one really useful review by Hot & Flashy specifically dealing with these two serums, but it also considered Timeless (which won) so it didn't shed a lot of light on the tie. The packaging on Paula's Choice might be a bit better since it has a rubber seal to reduce oxidation, but apparently it doesn't so much so null. 

So, I guess it's a tie.

The Best Vitamin C Serum That's Natural

Although my days of strictly natural beauty are behind me, I totally understand and respect the value system surrounding natural beauty. I think it's important to support and scrutinize the natural beauty industry the way we do the conventional beauty industry so that formulations continue improving. 

There should always be a natural option. Just because you choose natural doesn't mean you always have to go the DIY route. Which you can btw, if you're into that sort of thing. There are a ton of recipes out there. 

The Analysis

The biggest challenge to identifying the best natural vitamin c serum is first identifying which serums qualify as natural. The problem is that "natural" isn't a good concept. Alcohol is natural but you probably don't want to slather a lot of it on your skin.

On the other hand, a lot of the products that self reported as being natural had ingredients that some natural beauty enthusiasts might have issue with including methylsulfonylmethane (MSM), phenoxyethanol, and ethylhexylglycerin - which are totally innocuous but don't sound natural.

Case in point: vitamin C is ascorbic acid, sodium ascorbyl phosphate, tetraisopalmitate - these names would set off alarm bells on an ingredient list but they're not only totally safe and non-toxic but also highly effective and clinically proven to make your skin healthier. 

This is a lot of the reason I moved away from strictly natural beauty to a more non-toxic approach. Natural isn't a very useful concept for skin care. But anyway, I digress. That's just my opinion and of course to each their own. If you want natural, then natural you should get.

For the purposes of this review I'm going to go with the the products that are self reported as natural, but I've included full ingredients lists so you can make you own judgment call.

The criteria for comparison aren't as objective when it comes to natural serums. There is no gold standard formula. As such, I weighed relative concentration of active ingredients as the main criteria. 

best natural vitamin c serum

** Oliology serum is natural but didn't make it to this list because it isn't really widely available. As far as I could tell it's only at Winners (<3) in Canada. In any case it wouldn't have scored top points because it doesn't have any actives. 

Mad Hippie Vitamin C Serum

mad hippie vitamin c serum

The top two contenders are InstaNatural Vitamin C serum and Mad Hippie Vitamin C Serum. Both have sodium ascorbyl phosphate along with vitamin E and ferulic. For the best vitamin C serum the tie breaker was cost, but in this case it's cult status. Mad Hippie is the eponymous natural vitamin C serum. If you've done any digging at all, you've probably heard of this one. It's trusted and loved by a lot of people seriously into skin care. 

Runner Up: Instanatural Vitamin C Serum

instanaturals vitamin c serum

If there was a runner up of course it would be InstaNatural, an all around good formula just from a brand with a little less clout. However, also a really great first choice if you want natural but also cost effective. It's about $15 less than Mad Hippie, which can go a long way if you're on a tighter budget. 

The Best Cruelty Free Vitamin C Serum

Drunk Elephant C-Firma

drunk elephant c firma day serum

As per the analysis for best serum overall above, the best serum overall also happens to be cruelty free.

Runner Up: Timeless 20% C + E + Ferulic

If you're looking for something less expensive or without oil, Timeless 20% C + E + Ferulic is an excellent choice and also the top choice for best entry level serum.

timeless 20% vitamin c + e + ferulic acid serum

The Analysis 

I'm really happy to say that there are really a lot of cruelty free vitamin C serums. To find the finalists I cross referenced my list of top scoring serums with my list of cruelty free serums. There were 5 finalists (Cellex-C Advanced, Timeless 20% C + E + Ferulic, The Ordinary Vitamin C Suspension 23% + HA Spheres 2%, Cosmetic Skin Solutions C + E Advanced Formula, and Paula's Choice C15 Superbooster.) Timeless won simply because it was themes cost effective and had the fewest irritants in addition to being cruelty free. 

The Best Vitamin C Serum Free Of Irritants 

It's hard enough finding the right serum without specific sensitivities. This quick reference makes it a bit easier to see what's what at a glance. As it happens a lot of the top performing serums are also free of the most common irritants.

common irritants in vitamin c serums

Timeless Skincare 20% C + E + Ferulic

timeless skincare vitamin c serum

It's a little difficult choosing a pick for this category since there are so many sensitivities it makes objective quality criteria difficult. If you are okay with any concentration of ascorbic acid and don't find vitamin E sensitizing Timeless 20% C + E + Ferulic is a solid entry level pick. If you want a bit of an upgrade Cosmetic Skin Solutions Vitamin C + E Advanced Solution and NuFountain and good mid-range choices, and on the very high end Cellex-C Advanced C and SkinCeuticals CE Ferulic

All of these options have clinically proven formulations, so you wouldn't be compromising on performance. 

Runner Up: CSI Vitamin C+ 12% Youth Serum

csi vitamin C+ 12% youth serum

If you have a lot of chemical sensitivities but are okay with ascorbic acid then a good pick is CSI Vitamin C+ 12% Youth Serum. It's only 12% ascorbic acid and one other ingredient (butylene glycol) so it's a good option for those who want the benefits of ascorbic without any potential irritants at all.

The Best Vitamin C Serum for Sensitive Skin

Ascorbic acid may be irritating to especially sensitive skin. If you have sensitivities but know you can tolerate ascorbic acid, then the previous analysis for oil free / silicone free / alcohol free / fragrance free is probably a better bet. 

If you can't tolerate ascorbic acid, things get a bit trickier. Vitamin C derivatives aren't as well studied as ascorbic acid so there isn't a lot of information on what performs best. However, having all the information in one place makes it a bit easier to spot irritants and avoid trouble. 

vitamin c serums cheat sheet ascorbic acid to derivatives comparison

Silk Naturals Super Serum 3% MAP

silk naturals awesome sauce

It's difficult for me to make a one-size-fits-all recommendation for this category since there are so many factors, but if I had to ​it would be any of the Silk Naturals serums

For one, the Silk Naturals serums have a huge cult following so there are tons of reviews online from sensitive skinned reviewers who generally seem pretty happy with their results. For another, MAP is clinically proven effective but with less irritation. Some say it's as effective as L-AA, but I haven't seen the data myself. I've also read that MAP converts to L-AA in the skin, which is why it's so effective as compared to SAP which does not convert. That being said, SAP is still (for some reason) effective so if you find MAP is irritating then SAP might be a good bet. 

Otherwise as compared to other derivatives MAP is a good starting place. The only other derivative with supporting data is tetraisopalmitate, which is a lot more expensive than ascorbic acid and still needs a fairly low pH (as far as cosmetic formulations go) of 5 to remain stable. 

Silk Naturals Awesome Sauce is probably a good place to start since it's only 3% MAP and got the highest score of all the Silk Naturals serums in my ranking because of a lot of good reviews. The only reason Silk Naturals didn't get higher points in my ranking is because they don't have the clinically proven formula of ascorbic acid, vitamin e and ferulic. But if you can't tolerate ascorbic, then it doesn't matter anyway. 

Vitamin C Serum​ Benefits

Vitamin C is a natural antioxidant that plays a big role in the body and in skin care because it prevents the damage caused by free radicals while also improving the health of tissues by supporting collagen synthesis.

Free Radicals​

For the most part what we think of as aging is the visible signs of tissue damage caused by free radicals. Free radicals come from our normal metabolic processes, they come from sun exposure, they come from smoking, and they come from air pollution.

These radicals have a potential to start chain or cascade reactions that damage the cells. The harmful effects….occur as direct chemical alterations of the cellular DNA, the cell membrane and the cellular proteins, including collagen. Vitamin C in dermatology

Free radicals have been implicated in a lot of the most common diseases affecting the western world including heart disease, diabetes, cancer and dementia. They form when certain molecules come into contact with oxygen and lose an electron, making them highly unstable “reactive oxygen species.” When there are too many of these reactive oxygen species and not enough antioxidants to balance them you get oxidative stress. 

Oxidative stress is what makes people sick, what turns apples brown and according to the free radical theory of aging it’s what makes us age. 

There are numerous studies that demonstrate that ROS and oxidative damage increase with age and that reducing oxidative damage extends the lifespan of various model organisms (yeast, nematodes, fruit flies, mice, etc.), as well as that increased production of ROS shortens lifespan. The Free Radical Theory of Aging Is Dead. Long Live the Damage Theory!

The free radical theory of aging has been disputed, with a lot of criticism coming up due to the fact that we can’t prevent damage entirely i.e. why don’t we live forever? Granted, the damage control potential of antioxidants in the aging process may be finite, but there’s more than enough clinical and anecdotal evidence that shows that antioxidants like vitamin C neutralize free radicals, which gives a significant number of people visible improvement in their skin. That alone is saying a lot more than your average drug store moisturizer, sans actives.

Interesting Side Note

Unfortunately, like most complicated issues the solution isn’t black and white. We can’t just neutralize all free radicals. For one, we need to breath. For another, free radicals are actually necessary for our immune systems to function. They may even prevent cancer.

It makes sense. In other aspects of our physiology and psychology the right amount of stress (aka eustress) is not only beneficial but also necessary. It’s what makes us and our cells adapt and thrive.

Sun Exposure​

Sun exposure deserves it’s very own mention because it’s one of the most common sources of free radical induced skin damage. There’s a reason sun protection is one of the cardinal rules of skin care. The evidence is pretty much overwhelming. 

Sun exposure promotes the ageing of your skin due to a combination of several factors. UVB stimulates cell proliferation in the outer layer of the skin. As more and more cells are produced the epidermis thickens. UVA penetrating into the deeper skin layers disturbs the connective tissue: the skin gradually loses its elasticity. Wrinkles, sags and bags are the common result of this loss of elasticity. A phenomenon often seen in elderly people is the localized over-production of melanin resulting in dark patches or liver spots. Furthermore, the sun’s rays dry out your skin making it coarse and leathery. World Health Organization

It messes with your skin’s homeostatic balance. It upsets the processes that regulate cell turnover and melanin formation.

The goal and purpose of anti-aging is to prevent further damage. For most of us that’s not enough. We also want improvement and glow. Topical vitamin C is a great all around active because it not only prevents the signs of aging by neutralizing free radicals, it also improves skin’s appearance by supporting collagen synthesis and regulating skin cell turnover. 

Interesting Side Note

Sun exposure produces vitamin D at a rate of up to 1000 IU per minute. Vitamin D supplements range from 1000 IU to 5000 IU. So 15 minutes of sun exposure is equivalent to 5 high dose vitamin D supplements.

Anecdotal & Clinical Evidence for Vitamin C Effects​

Aging & Anti-Aging​

Clinical​

The majority of the clinical studies I've been able to find on topical vitamin C relate to it's photoprotective effect, but there are also a few studies that look at it's role more broadly in skin function.

  • In a 3 month double blind study 19 volunteers between the ages of 36 and 72 were randomly assigned unmarked medications to either side of their faces. The active medication was 20% ascorbic acid serum (Cellex-C) and the non-active was the serum base. Three drops were applied daily for 3 months. Optical imaging analysis showed statistically significant improvement in the area treated with ascorbic acid. Patient questionnaires and photographic assessment also showed significant improvement. Use of topical ascorbic acid and its effects on photodamaged skin topography.
Anecdotal​

​It's hard to say whether I've had any anti-aging benefits yet but I think it's way too soon to tell. Up until about 4 weeks ago I used to only use vitamin C for micro needling treatments. Now I'm using it twice a day without fail. I've noticed a lot of improvement overall in my skin tone, texture and acne. I have a few lines on my forehead that do look less pronounced, but I think that might be a combination of things including a more gentle and hydrating skincare routine and hyaluronic acid serum in addition to the vitamin c serum.

Acne​

​Unfortunately there aren't a lot of clinical trials or other resources related to acne and vitamin C. The few that I could find are promising but a bit narrow in scope.

What we do know is that antioxidants cause statistically significant improvements in acne, either directly by supporting wound healing or indirectly by regulating cellular turnover (aka supporting normal keratinization.)

  • An open-label study (no placebo) of 60 acne patients found 5% SAP lotion applied for 12 weeks was statistically superior to 5% benzoyl peroxide, a widely prescribed acne treatment. The researchers also discovered that 1% SAP had an antimicrobial effect on acne bacteria in vitro. In a separate in vivo study of 20 patients treated with 5% SAP showed a 40% researchers found a reduction in UVA induced sebum oxidation i.e. blackheads. The conclusion was that “SAP is efficient in the prevention and treatment of acne vulgaris. SAP can be used in a non-antibiotic and effective treatment or co-treatment of acne with no side effects, which makes it particularly attractive for cosmetic purposes.” Sodium ascorbyl phosphate shows in vitro and in vivo efficacy in the prevention and treatment of acne vulgaris.
  • Another study found that 5% SAP lotion reduced acne inflammation by almost 50% in 8 weeks (20% in 4 weeks.) The same study found that 5% SAP was slightly more effective combined with 0.2% retinol, which created a synergistic effect. Comparison of clinical efficacies of sodium ascorbyl phosphate, retinol and their combination in acne treatment.
SAP VS ASCORBIC ACID FOR ACNE

​At present these are the only studies I can find related to acne and vitamin C. I was surprised to find that there weren't more studies related to acne and ascorbic acid. Given that ascorbic acid is generally considered more potent than SAP it stands to reason that it would be better for acne. In any case we don't know for sure. It could be that ascorbic acid would be better (notwithstanding any possible irritation as a side effect of the acidity) or it could be possible that there's something specific about SAP that improves acne.

ANECDOTAL

Vitamin C doesn't seem like it would be good for treating acne. For one, it's a pretty acidic active. It can sting going on, and this is especially so over open sores. It's like rubbing a lemon on a paper cut. That doesn't seem like it would do the paper cut much good, does it?

From my own experience other acidic actives like glycolic haven't ever done my acne good. They not only sting, but they don't do anything to speed healing or nourish the wound. If anything glycolic seems to make my pimples angrier. I know that isn't the case for a lot of other people based on want I've read on forums like r/skincareaddiction. As with everything in skincare YMMV.

In any case I assumed it would be the same for vitamin C but I'm happy to say I was wrong. Vitamin C really speeds healing for me. Whereas before a pimple would take anywhere from 8 days to 2 weeks to heal, now they take 3-5 days. That alone is enough to convince me to keep slathering it on twice a day.

The Potato Demonstration ​

​One day I came across this neat video on Instagram showing the effect of vitamin C serum on half an apple. of course, the side treated with vitamin C didn't turn brown (or oxidize.) Perfect demonstration of antioxidants in action. I wanted to see it for myself so I designed a little experiment. I didn't have apples so I used potatoes instead because they also oxidize and turn brown quite rapidly.

As a happy coincidence they also have a very similar pH to human skin, so I reasoned that the vitamin C serums would be reacting with a pH they're specifically formulated to work with. Apples have a pH of around 3.5. Potatoes are 4.8 to 5.4.

I used 2 kinds of vitamin C serum (Amara Organics 20% SAP and Cosmetic Skin Solutions 20% ascorbic acid) as well as lemon juice, white vinegar and nothing as a control. I took pictures at different time intervals starting at 5 minutes after first application all the way to 24 hours after. I reapplied 3 times during the 24 hour period.​

Obviously this isn't scientific but it's still a neat way to see the way vitamin C works compared to other things (or nothing.) There are a few things that I noticed in this experiment.

  • The Amara Organics treated potato looked really good for the first 12 hours but then oxidized really fast.
  • On picture 3 a dark spot can be seen forming on the potato treated with the Cosmetic Skin Solutions serum. After reapplication the dark spot disappeared and isn't visible anymore in picture 4. I thought that was absolutely amazing. It reversed damage on what was for all intents and purposes a dead vegetable...imagine what it does for a living organism.
  • Vinegar is harsh.
  • Lemon juice did surprisingly well...so of course I wanted to know "why not lemon juice?"

Lemon Juice vs Vitamin C Serum​

I’ve been lurking around r/skincareaddiction for long enough to know that lemon juice on the face is bad, in the same way that big skin care faux pas like baking soda and St. Ives Apricot scrub are bad. But the truth is that I don’t know why, and the results of my potato experiment have made me more curious than ever. 

The reason that ascorbic acid serum is better than lemon juice is because lemon juice isn’t a good source of ascorbic acid. On the contrary it has a high concentration of citric acid. Citric acid has different properties from ascorbic acid. Citric acid is much more acidic than ascorbic acid, which means it’s more likely to disrupt the skin’s acid mantle, which can leave skin more vulnerable to bacterial or viral attack (read: breakouts.) Likewise, whereas ascorbic acid protects the skin from photo damage, citric acid can make the skin more sensitive to photo damage

Why Is Serum The Best Form of Topical Vitamin C?​

Serums are having a moment. Jessica Hagy makeup.com

 

In biology serum is a blood protein that separates out when blood coagulates. That obviously doesn’t explain what a cosmetic face serum is.

We know from experience that serums are made with a wide variety of clinically proven actives that are suited to a lot of different skin care goals and needs.

  • Topical retinoids are used for evidence based treatment of photo damage and acne.
  • Hydrators like ceramides, amino acids, and hyaluronic acid increase moisture retention and help build strong skin cell membranes while also replenishing and protecting the skin.
  • Anti-oxidants like vitamin C prevent and reverse the signs of photo aging including pigmentation and collagen degradation.

But what is a serum and is it really necessary? Isn’t a good moisturizer with actives the same thing without the extra step.

As I found the answer is no for a number of reasons.

In order to get a working description of serum I checked a few reputable online resources like Into The GlossHuffington PostGQmakeup.com and Paula’s Choice.

Besides the big guys I also found posts by blogger and esthetician Renée Rouleau and by a skin care start up called One Love Organics, as well as a thread on the topic on r/skincareaddiction.

As far as the first two pages of Google go (yes, I even ventured on to the storied second page of Google for this) this is all that’s out there.

Seems there are a lot of people talking about why you should use a facial serum, but not a whole lot who know what one is.

You are not alone in having no earthly idea what a serum is. Even if you’re the proud owner of several serums, it’s not a particularly clear product on it’s surface. Think of the contradictions: It’s moisturizing, but you still use moisturizer. It can be oily, but it’s not necessarily face oil. It can be watery, but is it essence? So many questions and we haven’t even gotten to ingredient lists yet! Into The Gloss

This sentiment is echoed by One Love Organics “While they can be moisturizing, serums are not moisturizers, per say – although a good one can serve as such.”

In spite of the confusion there does seem to be some consensus. The general idea is that serums are more concentrated, light-weight formulations.

The best serums contain high concentration and blends of these research-proven ingredients. Along with this prestige fusion of ingredients, serums typically have a distinguishing smooth delicate lotion, gel-lotion, or silky fluid texture. Paula’s Choice

Comparing Other Formulations: Cream, Lotion, Oil, Toner, & Powder ​

​Ascorbic acid is best in serum form because most other forms pose much more significant challenges.

Cream/Lotion

Oil

Toner

Powder

Vitamin c lotions and creams aren’t a good option for LAA because ascorbic acid is most potent at a pH of 3.8 or lower, which is highly acidic. Most lotions and moisturizers have a gentler pH of 5-7. Ascorbic acid degrades much more rapidly at the higher pH level of most moisturizers and lotions. Stable ascorbic acid serums are quite complex to make. The challenges of making a stable vitamin C face cream are even greater.

Vitamin C creams and lotions made from a derivative like vitamin C ester are fine, but not as potent. 

A formulation of pure vitamin C oil poses a few problems.

1. L-ascorbic acid is most effective in a water base. 

2. Double edged sword: If you use vitamin C oil or even an oil based vitamin C serum it should be layered over other actives in your routine, otherwise the actives may not penetrate effectively due to the oil. The problem is that vitamin C works best when applied before other actives, otherwise it loses some potency.

3. Oil formulations may cause breakouts for those with particularly acne prone skin especially if they contain comedogenic oils

The differences between vitamin C toner vs vitamin C serum are:

- Consistency: Serum is thicker, toner is a liquid. 

-Concentration: Toners are usually less than 10%.​


There are a few reasons to use a toner rather than a serum. Mostly it depends on personal preference and routine layering. If a toner fits better within a skin care routine then it may be a better option. Still, a serum gives much greater results because its so much more concentrated. If you do choose a vitamin C toner watch out for alcohol high on the ingredients list.

There's only one example of this that I know of (Philosophy Turbo Booster C Powder.) The problem with powder formulations is that users face the same stability issues as manufacturers. Ascorbic acid functions best at a pH of 3.5 or less. Any medium it's mixed with (including water) may increase the pH and make it ineffective.

Why Topical Vitamin C Works Best as a Serum

Ascorbic acid works best in serum form because it makes it easiest to control the formulation in order to ensure effectiveness. It also makes it easier to layer it with other actives. 

Sources

Primary

Changes in dermal papilla structures due to aging in the facial cheek region. Skin Res Technol. 2015 May;21(2):224-31.

Vitamin C in dermatology. Indian Dermatol Online J. 2013 Apr-Jun; 4(2)

Sodium L-ascorbyl-2-phosphate 5% lotion for the treatment of acne vulgaris: a randomized, double-blind, controlled trial. J Cosmet Dermatol 2010;9:22-27.

Epidermal homeostasis: a balancing act of stem cells in the skin. Nat Rev Mol Cell Biol. 2009 Mar; 10(3): 207–217.

Comparison of clinical efficacies of sodium ascorbyl phosphate, retinol and their combination in acne treatment. Int J Cosmet Sci. 2009 Feb;31(1)

In vitro antioxidant activity and in vivo efficacy of topical formulations containing vitamin C and its derivatives studied by non-invasive methods. Skin Res Technol 2008;14:376-380.

A topical antioxidant solution containing vitamins C and E stabilized by ferulic acid provides protection for human skin against damage caused by ultraviolet irradiation. J Am Acad Dermatol 2008;59:418-425.

The pH of the skin surface and its impact on the barrier function. Skin Pharmacol Physiol. 2006;19(6):296-302.

Ferulic acid stabilizes a solution of vitamins C and E and doubles its photoprotection of skin. J Invest Dermatol 2005;125:826-832.

Sodium ascorbyl phosphate shows in vitro and in vivo efficacy in the prevention and treatment of acne vulgarism. Int J Cosmet Sci. 2005 Jun;27(3)

Topically applied vitamin C increases the density of dermal papillae in aged human skin. BMC Dermatol 2004;4:13.

Topical ascorbic acid on photoaged skin. Clinical, topographical and ultrastructural evaluation: double-blind study vs. placebo. Exp Dermatol 2003;12:237-244.

Double-blind, half-face study comparing topical vitamin C and vehicle for rejuvenation of photodamage. Dermatol Surg 2002;28:231-236.

Topical L-ascorbic acid: percutaneous absorption studies. Dermatol Surg 2001;27:137-142.

Use of topical ascorbic acid and its effects on photodamaged skin topography. Arch Otolaryngol Head Neck Surg. 1999 Oct;125(10):1091-8.

The role of free radicals in disease.  Aust N Z J Ophthalmol. 1995 Feb;23(1):3-7.

Secondary

Vitamin C and Skin Care. Oregon State University Linus Pauling Institute Micronutrient Information Center

Probing Question: How do antioxidants work? Penn State News

http://www.thedermreview.com/vitamin-c-ester/

http://www.thedermreview.com/l-ascorbic-acid-acid/

https://www.truthinaging.com/review/get-to-know-your-vitamin-c

http://thebeautybrains.com/2014/05/which-kind-of-vitamin-c-is-best-for-skin-the-beauty-brains-show-episode-31/

http://www.lifeextension.com/Magazine/2016/6/Topical-Vitamin-C-for-Skin-Rejuvenation/Page-01

https://phamix.com/2008/11/topical-vitamin-c-different-forms-and-their-results/

http://theordinary.com/vitcguide

https://www.reddit.com/r/SkincareAddiction/comments/246th7/vitamin_c_ph_levels/

Disclaimer

This document is for informational purposes only and does not constitute medical advice. Although every effort is made to keep the information current and complete, the accuracy or completeness cannot be guaranteed.

Author

I write about wellness and ideas that make you better, whether that's a new book, a better way to travel, a skin treatment that works or an ergonomic aromatherapeutic work space. You are the biggest and most important project you'll ever work on. When you take the time to nurture and invest in yourself the returns will multiply through all facets of your life. If you want to have it all, begin with yourself.

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