Get the Most Out of Your Vitamin C Serum

How to Use Vitamin C Serum L-Ascorbic Acid Skinceuticals YouGlowGal You Glow Gal Esthetician Sarah Payne Hiatus Spa Dallas Skincare Beauty Blogger

If you Google how to use Vitamin C you’ll likely find a mix of opinions. The goal here is to clarify and provide guidelines for you to get the most out of your Vitamin C serum. There’s constant innovation in the beauty industry, so while I would suggest these rules for almost all forms of Vitamin C there are exceptions.


For the sake of this post, the information is specific to L-Ascorbic Acid


Vitamin C is known for two key benefits: it functions as an antioxidant with the ability to protect skin from damaging free radicals ( the bad guys who age our skin, create sun damage, and break down collagen ), and aiding collagen and elastin production to fight wrinkles, ensuring even skin tone and texture.

While working on these culprits of aging it Vitamin C brightens skin tone, fades hyperpigmentation and age spots, and preventing future damage. The majority of Vitamin C formulations are marketed as antioxidant treatments to prevent free radical damage in the skin.


Rewind… how does Vitamin C work?

Antioxidant serums work to prevent oxidative strain caused by pollution and UV radiation we’re exposed to during the day, so they’re ideal for use under a sunscreen.

Think of it like this: you’re at a bar with your girlfriends and off in the corner you see a hot mess having a little too much fun, and the bouncer kicks the hot mess out. Antioxidants and Vitamin C are the bouncers in your skin kicking out free radicals.

Clusters of cells in your skin break down over time and environmental aggressors speed up the process. Instead of having a cluster of 100 healthy cells, 10 become damaged from free radicals and fall off. Your cell cluster continues to regenerate by copying its self, but now it’s damaged so this leads unwanted issues like hyperpigmentation, skin cancer, wrinkles, etc. If you’re using an antioxidant it will bind to the missing parts of the cluster and continue to regenerate as a normal, healthy cell. Which leads us to…


Stable formulas

Stability of your Vitamin C serum is key. If it’s not stable it won’t be able to penetrate past the surface of your skin where it matters. I’m not a fan of DIY treatments or copycat budget formulas for this reason. It’s likely not passing through where it needs to to make the biggest impact on your skin.

Not all Vitamin C products are created equal, either. They need to fit within certain guidelines to remain stable, and even then many do not penetrate the stratum corneum. L-Ascorbic Acid needs to be under a pH of 3.5 with ingredients to aid in stability, commonly other antioxidants.

Some hold the belief that because of the instability of Vitamin C there’s no benefit in using one at all because as soon as it’s exposed to air and light they degrade. This couldn’t be further from the truth as stable, pH balanced formulas exist—you just won’t find them in your pantry or on Amazon for $25.


Guidelines for choosing a Vitamin C serum


Should I apply Vitamin C morning or night?

Always apply Vitamin C in the morning! L-Ascorbic Acid based treatments are intended for daytime use because of their ability to neutralize free radicals. Using your serum at night isn’t necessary because it creates a reservoir that remains in the skin when used daily.

If your Vitamin C serum is suggested to be used in the evening it may use a form that isn’t stable for daytime. If you’re unsure use this rule: if your serum is advertised as an antioxidant, use it during the day; if it’s promoted as a collagen, anti-aging treatment use it in the evening.


What about skin regenerating at night and creating more collagen?

Vitamin C accumulates in the skin, so there’s no need to apply at night to aid in collagen production. Your skin can still create collagen during the day, it doesn’t stop working when you wake up in the morning. If you’re applying an antioxidant serum in the morning your skin is protected against photodamage caused by free radicals, preventing collagen breakdown. If your concern is collagen production I would suggest using Retinol in the evening instead.


What about using it morning AND night?

Your skin can absorb no more than 20% L-Ascorbic Acid within 24 hours. Unless there’s a small concentration of Vitamin C in your serum there is no reason to apply both AM and PM. If your serum contains more than 10% Vitamin C my concern is the manufacturer wants you to use up the serum quickly so you’ll repurchase sooner, or the formulation may not build up in the skin like it should and needs to be used more often for efficacy. Most quality products would be a waste to use twice a day.


But what about Vitamin C being destroyed by the atmosphere?

A serum stabilized by other antioxidants provides no reason for concern as they protect each other and your skin. L-Ascorbic Acid has shown to protect skin from UV-induced erythema, superficial redness in the skin, when paired with Vitamin E. This proves your serum is working continuously throughout the day without being destroyed.


How often should I use Vitamin C?

Every. Single. Day.

L-Ascorbic Acid optimally accumulates in your skin after 72 hours. In theory, this means you could use your serum every 2-3 days, but for best results, you would want to use it daily for optimum free radical protection. We’re exposed to free radicals every day unless you live in a bubble… but even then, UV rays would get into your bubble. Unless it was a UV-protective bubble….


What should I avoid?

You could use AHA, BHA, and Retinol but you might experience irritation. It’s best to use your Vitamin C in the morning and use your exfoliating treatments and Retinol at night. However, avoid Copper Peptides as their benefits are similar and cancel out the benefits entirely when used with Vitamin C.


How do I layer with other products?

Always cleanse, tone, apply serum, moisturize, and finish with your SPF. If you’re applying another serum in your routine your antioxidant should go first so it can properly protect your skin.



63 thoughts on “Get the Most Out of Your Vitamin C Serum

  1. Hi Sarah. I recently purchased exuvianve AF Vit c individual capsules. The instructions for them are to use at night. I wanted to use the Vit C during the day for free radical protection. Do you have any insight why this product would be instructed to use at night? And if there are any contraindications if I used it during the day anyways?

    1. Hi Sarah, you mentioned to use vitamin c serum under 3.5ph, so can I use my Essence with ph5 and contain nacinamide ingredient before my vitamin c serum

  2. PHi Sara, I was curious what your thoughts are on letting your vitamin c absorb and then masking after? I saw someone do this on Ig, but wouldn’t that just wash off the LAA after u wash off the mask? Thanks !

    1. Hey Maria! If your mask stays on for a bit, 15-20 min or so, it shouldn’t be an issue. Estheticians do this all the time in facials with various serums and layering with masks!

  3. Hi, Sarah! I just turned 30 and am upgrading my skincare regimen. I recently added a French HA cream (Ialuset) as my moisturizer and also got some A313 (I’m sure you know it — a French pharmacy retinol) that I have yet to use because I’m a little scared of it, haha. Anyway, if I were using A313 at night and using the Skinceuticals CE fereulic as my serum during the day, do you think it would play well? Thanks in advance. I’m new to this side of skincare. 🙂

    1. Hi Katie! CE Ferulic plays well with retinoids. If your skin isn’t used to CE Ferulic and experiences any sensitivity space out the days you used them together. xx

  4. Agree or disagree to this regimen:
    Day 1 Morning: Vit C & Moisturizer
    Day 1 Night: Retina & Moisturizer
    Day 2 Morning: Vit C & Moisturizer
    Day 2 Night: Hydroquinone & Moisturizer
    Repeat. Like an every other day scenerio.
    Age 37 w lots of sun exposure

  5. Hi Sarah,

    Is it okay to use Skinceuticals C Serum and then apply a face moisturizer that contains the following ingredients?

    All Ingredients: Water/Aqua/Eau, Dimethicone, Butylene Glycol, Butyrospermum Parkii (Shea Butter), Glycerin, Cetearyl Alcohol, Isostearyl Alcohol, Caprylic/Capric Triglyceride, Theobroma Cacao (Cocoa) Seed Butter, Ceteth-20 Phosphate, Butylene Glycol Cocoate, Isodecyl Salicylate, Ceramide 1, Ceramide 3, Ceramide 6 Ii, Calluna Vulgaris Extract, Chondrus Crispus (Carrageenan), Dioscorea Villosa (Wild Yam) Root Extract, Glycine Soja (Soybean) Sterols, Hibiscus Abelmoschuss Seed Extract, Trifolium Pratense (Clover) Flower Extract, Sodium Hyaluronate, Linoleic Acid, Linolenic Acid, Ascorbyl Palmitate, Retinyl Palmitate, Tetrahexyldecyl Ascorbate, Tocopherol, Tocopheryl Acetate, Erythritol, Glycine Soja (Soybean) Oil, Caprylyl Glycol, Isohexadecane, Macadamia Ternifolia Seed Oil, Peg-40 Hydrogenated Castor Oil, Acetyl Octapeptide-3, Sodium Pca, Trehalose, Urea, Homarine Hcl, Hydrogenated Lecithin, Hydrolyzed Potato Protein, Hydrolyzed Soy Protein, Hydrolyzed Yeast Protein, Lauryl Peg-9 Polydimethylsiloxyethyl Dimethicone, Lecithin, Phospholipids, Phytosphingosine, Ammonium Acryloyldimethyltaurate/Beheneth-25 Methacrylate Crosspolymer, Ammonium Acryloyldimethyltaurate/Vp Copolymer, Ceteth-20, Cholesterol, Oleic Acid, Oleyl Alcohol, Peg-100 Stearate, Sodium Lauroyl Lactylate, Dicetyl Phosphate, Hydroxyethyl Acrylate/Sodium Acryloyldimethyl Taurate Copolymer, Polysorbate 60, Polysorbate 80, Polyquaternium-51, Ethylcellulose, Beta-Glucan, Hexylene Glycol, Xanthan Gum, Sodium Hydroxide, Thioctic Acid, Ubiquinone, Disodium Edta, Cyclohexasiloxane, Cyclopentasiloxane, Parfum/Fragrance, Benzyl Salicylate, Butylphenyl Methylpropional, Hexyl Cinnamal, Hydroxycitronellal, Hydroxyisohexyl 3-Cyclohexene Carboxaldehyde, Limonene, Linalool, Isopropylbenzyl Salicylate, Benzoic Acid, Methylparaben, Phenoxyethanol, Potassium Sorbate, Sodium Benzoate, Sorbic Acid, Triacetin, Chlorphenesin.

    Anything in the ingredient list that would cancel out the Vitamin C?

    Thanks for your help and advice.

  6. If I’m oil cleansing, do I oil cleanse first, then use the vitamin c serum, wait for it to dry and then add my essential oil based moisturizer?
    Should I add my moisturizer once dry, or after a few hours to let the vitamin c penetrate? thx

    1. After oil cleansing, make sure all residue has been removed so your vitamin C can penetrate and follow up with your moisturizer after–no need to wait unless you want to. xx

  7. Hi! What are your thoughts on Phloretin CF? I saw on that it was given only one star compared to other vit C serums by skinceuticals like aox or CE ferulic. I have small sun spots showing up that i want to treat but otherwise no other major concerns. Look forward to your insight! I get mistaken for being 10 years younger than I am so it must be Asian genes 😛 skin is combination, slightly dry in winter .

    1. Hi! Phloretin is a great serum! Between CE and Phloretin, you want to choose based on your skin type. When you’re dry, like in the winter, grab CE and when you’re more oily/combo go for Phloretin. To me it sounds like Phloretin will be your go to most of the year. I envy those genes btw!!! haha

  8. Hi!! My vit c serum just arrived today yaayyy! regarding this post, does this mean that I should not use snail mucin essence together with the vitamin c serum since the snail mucin has copper peptides? also I have comedogenic acne and my derma suggested Epiduo but forgot to ask about using it with vit c haha. Do you think I use vit c in the morning then Epiduo in the evening or is that too much for my skin to take since both are actives? thanks in advance!

    1. Hey! As far as the copper peptides in your essence, just alternate morning/night. Some Vitamin C can cause sensitivity, so if you start Epiduo I would suggest starting slow a couple times a week and slowly build up, but use your Vit C daily if your skin tolerates it. xx

  9. Hi Sarah,
    Thank you for sharing this valuable information.
    I have a question. at night routine, Should I Use a moisturizer after using the Vitamine serum?

  10. Hello! Your post is very interesting!
    I have it narrowed down to two options. Please give me your opinion on which one you think would be best.
    -Revision Skincare Vitamin C 30% lotion
    -VivierSkin C E Peptides

    Thank you!

    1. If it were me I would go with Revision for the sole reason that VivierSkin’s first and third ingredients listed are grapefruit extract and fragrance

  11. I am using a vitamin c serum with a pH of 3.
    The ingredients of the serum are purified water, ascorbic acid, hyaluronic acid, glycerin, niacinamide, 1.2 hexanediol, hydroxyethylcellulose.
    It contains 20% L-ascorbic acid and pure hyaluronic acid 70% as active ingredients.
    I copied above from the bottle of my vitamin c serum.
    Is this a good serum going by above information?

    1. From the included ingredients it sounds like a nice serum, but the 70% HA is….questionable. I highly doubt it’s really 70% and if they’re stretching the truth about percentages I would be concerned about how efficient the formula is, but that’s just me being cautious!

      1. Thanks for your reply 🙂
        Why do you doubt if they are actually using 70% hyaluronic acid?
        It’s not an expensive ingredient…is it too low on the ingredient list to believably contain 70%?

        1. 70% HA is excessive and unnecessary. Even if it’s an inexpensive raw material it would be wasteful to use that high of a percentage. 🙂

  12. Do you have any opinions on Niod Ethylated L-Ascorbic Acid 30% Network? The company claims are suspiciously hyperbolic. However, it is more cost-effective than the Drunk Elephant C-Firma that I currently use. I am planning to try it out for a couple of months but was curious if you had any insight into the validity of the scientific claims.

    1. I haven’t used their Vitamin C products, the way they describe their products is off-putting to me and steered me away. I do believe you get what you pay for, and I’ve yet to come across a budget Vitamin C that performs well enough for me to consider switching from a more expensive product. Drunk Elephant’s C-Firma is reasonably priced and the formula looks promising… if it were me I’d stick with it.

  13. I’ve read that vitamin c serum must be left on the skin anywhere from 10 min to 30 min before applying the next step of a skincare routine. How long should I wait after applying the serum? Is a wait time necessary for effectiveness?

  14. Skinceuticals gave me a terrible rash, so I switched to Timeless Vitamin C serum.I read that you don’t reccomend it.Can you explain why?

  15. Hi Sarah, I use Cerave lotion and love it. I’ve read that when using lotion with niacinamides, you should wait at least 25 to 30 minutes before applying when using with vitamin C or a BHA. Is this true? I’ve been using it with my Total turnaround and haven’t had any problems.

  16. I’ve read some troubling info regarding the long-term safety of triethanolamine in skincare. I’m sure it’s safe at the percentages generally used in skincare but I keeping fretting about it. I don’t know if I can give up my ce ferulic. Have you caught wind of the triethanolamine debate? What are your thoughts?? Thanks 😀

    1. I remember reading about it when I compared Timeless and Skinceuticals, read up on it again to familiarize myself, and it doesn’t concern me enough to stop using my CE Ferulic. It’s good to be cautious but not so much that we can enjoy life experiences. If your serum makes you happy, brings you confidence, etc. then, by all means, ENJOY it! <3

  17. Hi Sarah,

    Since drunk elephant vit c stays on the skin for 72 hours, should it be applied every 3 days or every day ?

  18. Loved this article, I’ve hearded that Obagi is a great substitute for the skinceuticals version, but they offer different percentages. For someone in their mid-twenties who is just starting out and has combo skin, which % would you suggest? Because I’ve heard that 15% is the optimal.

    Obagi offers: 10%, 15% and 20%

    Thank you!!

  19. What do you think about Drunk Elephant C-Firma Day serum? Just finished a bottle and wondering if I should re-purchase or try SkinCeuticals.

  20. Great suggestion! I just purchased a 20% Vitamin C and noticed one of my favorite vloggers uses it in her morning routine, and your post may have answered as to why.

  21. Hi Sarah,
    I’ve been using Skinceuticals C+E+Ferulic for over a year and love it. However, we’re going to be pregnant any day and i took a good look at the ingredients and am not happy with some of the filler ingredients. If I’m making my own Vitamin C serum, what are stable ingredients that you would recommend I add? I was going off a recipe I read that uses a good quality non-GMO vitamin C powder, some glycerin and some vitamin E.
    Thank you

  22. I know u repeatedly say an inexpensive vitamin c option doesn’t exist.. im sure you feel this way (or maybe to my heart and skins dismay, its very true) as im approaching 30 in a mere 6 1/2 mos.. I went from just a cleanser, once in awhile using a toner, spot treating with tea tree oil, and a DIY rosewater & filtered water facial Mist id use throughout the day and during makeup application to save from having to buy MAC fix+, and weekly to biweekly or triweekly DIY mask (usually greek yogurt, honey, tumeric, lemon juice, and tea tree oil), though the mask really depended on what my skin was needing (moisture&soothing, acne help&uneveness, or if I just wanted to brighten it up and work on lightening old acne scar dark spots, or prevent a breakout as much as possible while moisture bombing and Brightening (the Greek yogurt, honey, tumeric mask was and will be a staple again)

    Anywho, last week, I went to sephora after running out of glycolic acid serum which I really liked (didn’t upset my now, hit and miss sensitive and uneven reddened skin though normal bead like and clairasonic like things do)… i bought nip+fab glycolic cleansing pads instead of the serum, and had a reaction the first 2 days (my fault, I had tried pinterests cinnamon mask that morning and started Roc retinol cream 2 nights prior after my mom bought me the intensive night and eye creams… (so I OD on harsh new products)
    Anywho, while at sephora I looked at all the skin care lines I had sampled and liked the last 6mos or so, from beauty boxes or my sister n law (a psychologist who has 3 of everything possible by different brands ranging from high end, to “that is 2x my car payment almost for an eye cream or a mask!”…

    RELATED TANGENT– i quickly realized I couldn’t afford these items I liked that sephora sells (as im on disability, money goes to help my mom who is also my caretaker, co-pays, OTC treatment for fibro such as emu oil (sounds like gross holistic stuff, but does wonders for my hands and feet when I cant even make 1/2 a fist or walk.. also I’m hypoglycemic VERY severe (convincing my endocrinologist that I don’t need part or all of my pancreas removed alone was an ordeal, but she knows that when I’m not in a “remission” from doing a 3day complete fast which science is showing helps lower your pancreas and mutated pancreas beta cells from pumping out extra insulin my grocery bill can be a bit higher than most, almost all protein (mostly from liquid except usually dinner is solid) and fresh veggie (complex carbs, emergency fast acting sugars in every room in our house and my mom and my own purses, other than emergencies im almost no sugar (nothing in ose) and little carb,so my disability flies quickly (600-800 dollars is not alot in southern California esp with specialist to see on average 3-4 dr visits a mo with $20-60 Co pays, i get alot of labs done.. more comfortable pays.., and 12? Medications to fill and u guessed.. Co pays)
    even with 1 of the best insurance due to being disabled before 18, im permanently on my father’s and he has state of california government insurance, its GREAT.. if i wasnt on so many medications, blood work, and docs.. my parents help lots though
    all the nice brands Macy’s, Nordstrom, and now Sephora sells are simply impossible for me to afford unless I bought PERHAPS 1 a mo, maybe even then I’d be hard pressed…
    SO my question: I bought a few products on amazon before reading this, reviewing them Friday (its 4am Monday now)… max % hydraulic acid serum (never have had or used a serum, i like the consistency and how u can layer), and while all this when it comes to wrinkles is prevention, i do have bags and dark circles which I get from my mom who literally has had em since grade school (mine aren’t that bad, but worse than most in their 20s) and i have deep smile lines that are cute im told and go with my cheeks, but im also a gastric bypass surgery umm survivor? Lol bad word but im drawing a blank on how to say I had weight loss surgery (after losing 150lbs, 5’6 and270 to 120-127 I yo-yo daily based on water retention etc) but excess skin everywhere that sags down, got a tummy tuck but just realized last year that my face is a bit saggy and smile lines aren’t looking as youthful… ANYWHO, within mins of applying hydraulic acid, my smile lines lessened SOOO much and even my bags and dark circles improved which blew my mind (not just because this product was around $20, but 1) NOTHING has ever improved my smile lines and 2) no product without makeup lessened the darkness under my eyes 3) nothing improved my bags almost immediately
    4.) Only when I tried a $150+ hydraulic acid cream of my sisters did I have near this effect…
    Saturday i recieved more from amazon, including what you are probably going to burst my bubble about…
    I got the
    -Aztec clay mask (so many 5star reviews I have to try this!
    -Then I got a Body Body Merry night cream that can also be used as a day cream and since it is doing great on my fickle skin im going to use it am/pm … i bought it due to its 5% Niacinamide and the fact it had Peptides, plus this sounded good, PEPTIDES + OCEAN MINERALS + SEAWEED along with other natural/ organic ingredients such as Aloe + Hyaluronic Acid + Shea Butter + Jojoba Oil
    finally my HOPEFULLY HOLY GRAIL (super serum)
    -TruSkin Naturals Tea Tree Clear Skin Age Defying Forum 20% Vitamin C, 2.5% Retinol, 3.5% Niacinamide, 2.0% Salicylic Acid & 5.0% Hyaluronic Acid

    So, even though its all in a dark place (an ikea Alex drawer) it’s a fail im guessing….
    If in may I could only afford 1 item, what would you suggest?

  23. Thanks Sarah for this very informative piece. What would you recommend for a oily combo skin to use as Vit C? I am in my mid forties. Thanks,

  24. I don’t understand why you don’t like the Timeless serum, it’s below a PH of 2.5 and I am assuming if it doesn’t turn yellow it is stable, is this a false assumption. Is it because you believe it to be harsh at such a low PH? I agree with you that it should not be applied twice a day I like to apply mine ever 72 hours.

  25. I was just given a little sample of the SkinCeutical CE Ferulic so I came here for some advice on how to use it 🙂 Your posts are always very informative and I’ve learnt a lot. Though this product is very expensive and I doubt I’ll be purchasing the full size in the short term.


    1. You’re young, you can totally get away with using their AOX 10 daily and upgrade when your budget allows! That’s what I start my younger clients on 🙂 if you’re combo-oily CE Ferulic might be too heavy for your skin, though

  26. I’ve been using a vitamin c serum from amazon now I’m thinking I might bin it lol I didn’t think it was much good tbf anyway as it’s supposed to have 2.5 retinol in it yet u can use it morning and evening hmm I don’t think so

  27. Thanks for this thorough explanation about Vitamin C. May I ask, if you apply this during the day, do you follow the pH rule? Ie do you observe the waiting time after applying it before another skincare so that the different pH will not interfere the activity of Vitamin C?

    1. If you’re just following up with a moisturizer I don’t see the need to. I never wait… And I’ve had great results over the years.

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