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Vitamin C Serum


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SKU 19771

Refresh your skin with our Vitamin C Serum. Although it might not be suitable for individuals with sensitive skin, the acidity of Ascorbic Acid (L) will exfoliate and promote skin renewal. The vitamin C will help restore elasticity to aging skin, promote collagen synthesis, protect against UV Damage, reduce redness, promote wound healing, suppress melanin synthesis, and more.  

Vitamin C Serum can be purchased in premixed 15% and 20% form. For more options, check out this blog post for some DIY suggestions using ascorbic acid powder.

Click the expert details tab for complete information on Vitamin C and Vitamin C products.

This product is available in our Serum Quartet for 25% off.

Usage will depend on individual tolerance to the acidity of the serum. Test the serum on the inside of your arm first and rinse well if you feel any discomfort. The serum can be diluted with Sea Kelp Coral in order to make it more suitable for sensitive skin.

We recommend applying a thin layer of serum to clean skin once or twice weekly. Vitamin C Serum can be applied on the face, neck, or wherever your skin is in need of exfoliation and renewal, keeping away from the eyes.

Note: Be sure to wear Sunscreen as exfoliation may increase skin sensitivity.


Additional notes:

  • High concentration L-Ascorbic Acid serums, or even fresh L-Ascorbic Acid crystals dissolved in water, are great exfoliating options. 
  • Because over-exfoliation can cause inflammation and other problems, we recommend careful use of L-Ascorbic Acid serums. Usage once or twice a week is optimal for most skin types. Our Collagen Serum with MAP (Magnesium Ascorbyl Phosphate) is a great alternative for daily use, as it contains other valuable actives we cannot use in an acidic solution.
  • Do not worry about waiting for the acidity of the skin to go back to normal (it will take a few hours) before using most other products. If you are using products with complex proteins, such as our EGF or our antioxidant products, it is recommended that you wait at least an hour to ensure the proteins are not damaged.

Water, Ascorbic Acid (L) (Vitamin C),Glycerin, Hyaluronic Acid, Ferulic Acid, Phloretin, Pomegranate Seed (Punica granatum) Oil, Tocotrienols, Vitamin E Oil (Alpha-D-Tocopherol), AstaxanthinLycopeneLutein, Alpha Lipoic Acid, Beta Carotene, Xanthan Gum,  Lemon (Citrus limon) Extract, Orange (Citrus sinensis) Extract, PhenoxyethanolCaprylyl Glycol,Sorbic Acid.

The acidity, and by extension, the exfoliating strength of our Vitamin C Serum depends on how much powder is added to the serum base. The chart below shows the acidity of the serum compared to that of a simple solution of L-Ascorbic Acid crystals in water as the concentration of the crystals increases. A 20% concentration is pretty close to the maximum solubility and at that point you may see some crystals coming out of solution, especially in a refrigerated serum. The pH scale shows increasing acidity as the number goes down. 7 is neutral on the scale. The scale is exponential so a difference of 1 on the scale is a factor of 10 difference in proton concentration.

pH. Examples:

Skin Actives Sea Kelp Coral/ New Collagen Serum - pH. = 5.5
Skin Actives Salicylic Wash - pH. = 3.5
Skin Actives L-Ascorbic Acid Serum 20% - pH. = 2.1

We also measured the pH of some Vitamin C Serums on the market (notes by Lauren):

    Testing serum with a pH strip yielded a pH range of 3-4. His ingredient list is interesting, as no ascorbic acid is listed and is just assumed as part of the CamuCamu extract.

    Test strip yielded a pH range of between 4-5

    Test strip yielded a pH of 6-7. They claim to use calcium ascorbate in conjunction with vitamin C, which I personally haven't seen before. 

Vitamin C and Vitamin C Products

Vitamin C is a chemical, its chemical name is L-Ascorbic Acid. 

Deficiency of vitamin C results in scurvy, and the name “Ascorbic Acid” is derived from the Latin word for scurvy (scorbutus), a nasty illness whose (easy) fix, citrus fruit, eluded pirates and sailors until 1753.

Why is L-Ascorbic Acid a vitamin? Most animals can make their own vitamin C, but humans can’t, because somewhere along the line we lost a crucial enzyme, L-gulonolactone oxidase, required for the synthesis of L-Ascorbic Acid. This makes it an essential nutrient, i.e. we must get it by eating food containing it (or applying the vitamin to our skin).

 L-Ascorbic Acid is important for plants and animals because it works as an antioxidant.  More specifically, it is a water soluble antioxidant, and this means that it can work in almost all the reactions occurring in the cell. [Conversely, chemicals with vitamin E activity are lipid (oil) soluble and can work in the lipidic side of the cell membranes. They are both important, this is why they are vitamins!]

There is more to vitamin C than “just” the antioxidant side. In humans and many animals ascorbic acid is also a cofactor in the synthesis of carnitine (look this up in our website) and tyrosine (an amino acid) and it is required for the synthesis of collagen, wich is a very important protein in the skin. Collagen is a protein of complex structure, and the final protein we require is very different from the peptides initially made at the ribosomes. It is composed of a triple helix, which consists of two identical chains and an additional chain that differs slightly in its chemical composition. The amino acid composition of collagen is unusual for proteins with a high content of hydroxyproline. The peptides synthesized in the ribosomes undergo many modifications of their structure before they become collagen; among other modifications, proline (and lysine) residues in the peptides must be hydroxylated in a process catalyzed by enzymes that require ascorbic acid as a cofactor. The many symptoms of scurvy result from the inability of the human body to complete the transformation of the nascent peptides into collagen because of this lack of ascorbic acid. [Incidentally, here you see why it is silly to add hydroxyproline to a skin care product: this amino acid is NOT used in the synthesis of collagen. Proline is used and after protein synthesis, the proline residues are hydroxylated.] 

I prepared a complete overview of the properties of vitamin C, and its use in skin care products. The article is a little long so I have posted it in our forum ( The summary is as follows:


  • Vitamin C is a chemical, its chemical name is L-Ascorbic Acid. 
  • Why is L-Ascorbic Acid a vitamin? Most animals can make their own vitamin C, but humans can’t. We must get it by eating food containing it (or applying the vitamin to our skin).
  • L-Ascorbic Acid is important for plants and animals because it works as an antioxidant, preventing damage to cells from oxidation reactions.
  • L-Ascorbic Acid is also require to create collagen, an important protein in the skin.
  • Un-oxidized L-Ascorbic Acid acts as a strong antioxidant; oxidized L-Ascorbic Acid acts as an oxidant and will not be useful to the skin.


  • Ascorbic Acid (L) provides important protection against damage induced by UV radiation (and the DNA mutations and cancer that may result from it), improves skin elasticity, decreases wrinkles by stimulating collagen synthesis, reduces redness, promotes wound healing, and suppresses melanin synthesis.
  • Visually, the use of L-Ascorbic Acid improves wrinkles and decreases inflammation.
  • Glycolic and lactic acids are frequently used in peels because they are weak acids that will do their job and later be metabolized by the skin. L-Ascorbic acid is also a AHA and useful for an acidic peel. [See below for information regarding the strength of Vitamin C Serums as an exfoliant]


  • Chemical derivatives such as MAP (Magnesium Ascorbyl Phosphate) offer advantages such as stability and an acidity level that can make them more suitable for skin care products. 
  • MAP is a good vitamin C derivative, because it has been shown that it penetrates the skin and in the skin it is converted to L-ascorbic acid. As for the most important question, is it an actual vitamin C? MAP has been shown to protect the skin from UV damage and prevent synthesis of melanin, just as L-Ascorbic Acid does. This is why, in our popular collagen serum, you will find MAP and not L-Ascorbic acid.
  • Sometimes an oil-soluble version of vitamin C is wanted for a special formulation, and for that, we turn to Ascorbyl Palmitate. But it must be remembered that the principal role of vitamin C is as a water-soluble antioxidant.
  • It is important not to combine vitamin C with metallic ions such as Copper or Zinc in a formulation.
  • A 20% concentration is pretty close to the maximum solubility and at that point you may see some crystals coming out of solution, this will occur more frequently in a refrigerated serum. If the vitamin C comes out of solution, warm the serum up a little and shake well.


  • It is very important that vitamin C products contain un-oxidized L-Ascorbic Acid. Old products with oxidized vitamin C can cause damage to the skin.
  • In non-acidic formulations, like our Collagen Serum, it is important to use a vitamin C form like MAP or Ascorbyl Palmitate.
  • At an acidic pH, L-Ascorbic Acid will be quite stable. The shelf life of the serum will depend on the acidity of the serum.
  • Our new best estimate is that a serum with a pH of 2.5 will have a shelf life of around 6 months.
  • Because of the above point, we suggest checking the pH of any L-Ascorbic Acid serum and ensuring that its pH is below 3.5 (pH. strips can be purchased to measure this).
  • Refrigeration slows the oxidation of L-Ascorbic Acid and extends the lifespan of the serum. 
  • Alpha Tocopherol and Ferulic Acid are added to L-Ascorbic Acid serums to delay the oxidation of vitamin C.
  • It is very important to make sure that you do not use oxidized L-Ascorbic Acid Serums. Make sure your product contains a 'made on' or 'use by' date. Do not use a product that is over 12 months old as it will not be useful to the skin. If mixing your own water/ascorbic acid mix do not keep the solution for more than a few hours. Refrigerate the products if possible.

Vitamin C Links

L - Ascorbic Acid ( to create your own serum or mix into water as a simple wash)
Magnesium Ascorbyl Phosphate (for a stable, less acidic mixture compatible with complex actives)
Ascorbyl Palmitate (an oil soluble ester)
Vitamin C Serum (our ready-to-use L-Ascorbic Acid Serum)
Collagen Serum (our best anti-aging serum, containing MAP, EGF, and other actives)

Customer Reviews**

  • Author: Mary Lord
    I LOVE this new C Serum. It goes on very silky and gives my skin a matte shimmery glow. I also love the convenience of a premix but made fresh C Serum. Mary
  • Author: Mari
    I gave this to my mother to try as she is a smoker and has lots of medical condition requiring mountains of meds so her skin is always a little dull, dry and grey, if unlined. After a month she reported getting lots of compliments on her skin and it was brighter and smoother. I then gave her anti-ageing cream to use along with it and her skin just transformed and is smooth and radiant.
  • Author: Karenv
    I bought the mix-it-yourself kit and started out with a small amount of the vitamin C in the serum and gradually added a little more to the bottle as my skin got used to it. It made my skin smoother and a little glowy (word??) :) It seems to smooth out the sun damage too. I wish we could buy the serum bottle separately as I still have some of the dry ascorbic acid mixture left over. I hope to keep increasing the ratio of ascorbic acid to serum.
  • Author: David Dinh
    I think this is a very good and potent formula. However, I was shocked to discover that the pH of the products (premixed 15% version) is actually around 1.5 which is really low for a vitamin C serum (a staff gave me this information), which is different from the 2.5 pH on the expert details tab. I honestly believe SAS should readjust the pH of the products around 2.5-3ish so this can be used more frequently like other L-AA serums on the market.

    Other than that, this product has worked really well for me.
  • Author: Tina Colovin-Hu
    Excellent formula, thank you team Skin Actives! I have tried many vitamin C products but have found most often the PH is around 3-3.5; which is not the best for my skin. I have built up the tolerance for a PH of 2.1 (best absorption). Under the comment section, I see one customer suggested changing the PH level, please DO NOT change anything. This formula is perfect as is.

    I am a bit disappointed to see SAS has removed the "mix it yourself" option. I really like this with the 20% formula and hope you will bring it back. If crystals are a concern, perhaps consider selling a handheld mini mixer. Amazon sells one for about $12, great for small liquid mixes. The attachment is small enough to fit into the top of a 1oz. bottle (just to demonstrate the size). The mixing element is plastic.
  • Author: Anisa
    I had bad experience with LAA serum in the past but really wanted to incorporate it in my routine. Apparently the serum was too strong at 20% and irritated my skin horribly. I mix this in 12% concentration and it's perfect. This serum gives me the glow and very hydrating on my skin that when I ran out my skin was suffering. After 7 months of use, I don't even need concealer for daily makeup.

    However, I was mortified when I noticed they no longer offer the Mix Your Own Kit. That kit is a blessing for someone like myself who lives in the other side of the globe since I never needed to worry much about the freshness of my serum and I can save a bit of shipping by purchasing a couple sets at once since the shelf life is pretty long if the serum stays unmixed. Plus, the convenient on tailoring the strength is a blessing for my skin that's a bit on the sensitive side.

    I beg, beg, beg you, please bring back the Mix Your Own option!
  • Author: JB
    I love this serum but I'm so disappointed that the Mix Your Own kit is no longer available.

    Like other reviewers, I love everything about this serum (including the pH - please don't change that), but part of the magic was the ability to easily lower the concentration and then gradually raise it as the health of my skin improved. Being able to mix up small amounts also gave me the peace of mind that it was fresh and un-oxidized. With pre-mixed versions, I'm always racing the clock to use up the whole container before it starts to degrade.

    The DIY option made this product stand out from all the other similar C Serums - I really hope you'll bring it back!
  • Author: Suzanne Stanford
    Not a fan of this formula. I previously used the DIY Vitamin C Serum, which was very simple in its ingredients. There is something in this premixed version that is clogging my pores. Since I have somewhat dry skin, that rarely happens.
  • Author: Zeyna
    It's so disappointing that you've discontinued the Mix Your Own kit. I loved that you can tailor the serum to your own needs.
    Please bring back the Mix Your Own kits please. Or atleast make it easier for us to customize our own serum by selling the serum base separately.


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