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The Ultimate Guide to Vitamin C in Skincare

There are a few staple skincare ingredients out there that everyone should know about, and one such is the tried and tested active ingredient - vitamin C! Not only does it help protect skin from damage, but it also improves its appearance. If it’s not in your bathroom cabinet right now, it might very well be after reading this...

What is vitamin C?

It’s in our food (oranges, lemons, peppers and broccoli to name just a few examples), it’s in our medicine cabinet (even if you don’t have vitamin C tablets, specifically, it’s probably in your multivitamins and Barocca) and, now more than ever, it’s in our skincare! Yep, vitamin C is one of the most celebrated ingredients in the world of skincare. That’s because applying it to our skin does so many fantastic things!

You’ll likely come across a few different variations of vitamin C, though, which can be a bit confusing. For example, you might have heard the term L-ascorbic acid (or ascorbic acid). This is vitamin C in its purest form. Then, there are a load of vitamin C derivatives, and that is where it gets confusing! Sodium Ascorbyl Phosphate, anyone? How about Magnesium Ascorbyl Phosphate, Ascorbyl Tetra-Isopalmitate, Ascorbyl Palmitate or Ascorbyl Glucoside? MIND BLOWN! You can find these in serums, creams and more! I'll come back to this in more detail in a mo.

Why should you include Vitamin C in your skincare routine?

Ok, here’s the good bit… Vitamin C is absolutely incredible for doing several things to the skin. The first thing is that it’s an amazing antioxidant, working as a barrier to protect the skin from free radicals (microscopic wrecking balls which wreak havoc in the skin!) during the day and helping it recover from a day full of environmental exposure at night.

The next key benefit of vitamin C is that it brightens, so if your skin is feeling a little dull, this could be the ingredient to remedy it. It’s also great for helping boost collagen and elastin and, as a consequence, helps reduce the appearance of fine lines and wrinkles. And I’m all for anything that can do that!

Another benefit of vitamin C in your skincare routine is that it evens skin tone and signs of hyperpigmentation, and improves skin texture. So, if this is something that’s been bothering you or making you feel self-conscious, it might be worth adding it into your skincare regimen.

What kind of vitamin C is the best?

That depends on what you mean by best! As with all active skincare ingredients, the reason they are called active is that they actually stimulate cellular changes in the skin. The rate at which they stimulate these changes is determined by their potency and the percentage of the active ingredient in a product. Whilst the higher percentage, more potent actives REALLY get to work on the skin, the downside of this is there are more potential undesirable side effects.

So, whilst a high percentage vitamin C serum might tackle dullness, hyperpigmentation, skin tone and plumpness, you may well experience some not so great effects like irritation and itchiness.

You have probably noticed that vitamin C is called different things in different products. It’s pretty confusing, isn’t it. It means that there isn’t a “one size fits all” approach to vitamin C formulations. The best product for your best friend may not be the best product for you.

Let me explain...

L-ascorbic acid (LAA) - ‘true’ vitamin C - is the biologically available form, the one your body can use without any fuss BUT it’s an aggressive, unstable beast! It doesn’t like being exposed to different temperatures, UV, air and other environmental factors. It’s pretty high maintenance!

For this reason, it's hard to formulate, which means it’s often pretty pricey. It basically mops up free radicals, and you want it to do this once it’s on your skin, not whilst it’s sitting on your bathroom shelf, as once it’s oxidised, it is ineffective.

So whilst it’s clinically effective, it’s also a bit of a skincare diva!

Vitamin C derivatives, on the other hand, are more stable and they last longer, which makes them a popular choice for many skincare companies. The downside is that when we use vitamin C derivatives, our skin has to do a bit of work converting them into ascorbic acid first. There’s an extra step in the process from applying your product to it working, so they are often gentler and slower to act. That said, derivatives are a great option for those with sensitive and reactive skin. If you’re after a gentler form of vitamin C, look out for products containing:

-Sodium Ascorbyl Phosphate (SAP)

-Magnesium Ascorbyl Phosphate (MAP)

-Ascorbyl Tetra-Isopalmitate (VC-IP)

-Ascorbyl Palmitate (AA-PAL)

-Ascorbyl Glucoside (AA-2G)

Let's demystify this for you!

Here’s a bit more detail about each of the types of vitamin C and some of the products you will find them in.

What is L-Ascorbic Acid?

L-ascorbic acid is, as we mentioned earlier, the most effective, bioavailable form of Vitamin C. It is such a powerful antioxidant it is oxidised by UV and air, so it should be stored in opaque or amber glass bottles.

Here are some important things to know about it...

  • Oil-based
  • Low pH
  • Highly efficacious
  • Great choice for those with hardy, oily skin


  • High chance of skin irritation
  • Needs time to absorb into the skin before layering with other actives
  • Build up % over time
  • Avoid delicate eye area

Here are some of the products you'll find on the market featuring LLA:

SkinCeuticals C E Ferulic

AlumierMD EverActive C&E + Peptide

Obagi Professional-C serum

Medik8 Pure C15

Inky List Vitamin C 30%

What about the derivatives though? Let's take a look at some of the most common...

What are Sodium Ascorbyl Phosphate (SAP) and Magnesium Ascorbyl Phosphate (MAP)?

  • Water-based; some prefer this texture over oil-based
  • Hydrating and gentler than LAA
  • Stable at a neutral pH
  • Great choice for those with sensitive, acne-prone skin as it’s effective against P. acnes, the bacteria that cause acne


  • Scientists aren’t really sure how much of the derivative is actually converted into LAA in the skin, so it’s probably better as a preventative step against ageing versus a reparative one.

And the products that include these ingredients?

Inky List C-50 Blemish Night Treatment

Glossier Super Glow serum

What about Ascorbyl Tetra-Isopalmitate (VC-IP) and it's key features?

  • Oil-based
  • Very stable, easy to formulate, longer lasting
  • Pretty good at penetrating the skin and getting converted to LAA
  • Great if you have sensitive skin and like an oil-based serum

Products that feature VC-IP include...

Dr Dennis Gross C + Collagen Serum

Paula’s Choice Resist Super Antioxidant Serum

And Ascorbyl Palmitate (AA-PAL)? Here's what you need to know...

  • Sometimes called vitamin C ester, AA-PAL
  • Oil-based
  • Very stable, easy to formulate, longer lasting
  • Gentle enough to be used on the delicate eye area
  • Shown to have some positive effect on pigmentation and may be effective in stimulating collagen production.


  • Fewer studies have been carried out on how well it converts to LAA in the skin

Products containing AA-PAL include...

Drunk Elephant C-Tango Multivitamin Eye Cream

Last but not least, Ascorbyl Glucoside (AA-2G)

  • Made by joining LAA with glucose...sugar
  • Water-soluble
  • Very stable, easy to formulate, longer lasting
  • Great for younger, sensitive, reactive skin


  • It’s nowhere near as potent as LAA, so better as a preventative measure

The products containing AA-2G?

Paula’s Choice Boost 10% Niacinamide Booster

Inky List 15% Vitamin C +EGF Serum

Is the percentage of vitamin C in a product important?

Yes. Just because a product says it has vitamin C and it smells like oranges, doesn’t mean it has the right type of vitamin C, in efficacious amounts!

The efficacy of L-ascorbic acid increases as the percentage increases - up to 20%. The same is likely true of vitamin C derivatives. It’s recommended that you work up to higher percentages of vitamin C, giving your skin a chance to adapt at a pace that is comfortable.

What are some of the potential side effects of vitamin C in skincare?

Vitamin C in skincare is well tested and can safely be used, daily, alongside other anti-ageing skincare products like retinoids, SPF and acids.

Minor adverse reactions to particularly potent products include irritation, redness, itching and a tingling sensation as you apply it to the skin.

It is important to listen to your skin when you introduce new products. Applying every second or third day, and working up to daily application is often a good way to gently introduce new vitamin C products into your regime.

When should I apply Vitamin C?

Hmmm AM or PM? Well, the debate’s still on with regards to this. Some say that you should use vitamin C in the morning, alongside your trusty SPF, to help protect your skin barrier from the day ahead. There are tonnes of things that our skin has to ward off on a day to day basis (sun, UV rays, pollution…) and it’s said that vitamin C is great for helping with this. But for others, vitamin C is an evening skincare staple. They say that it’s a great way to help your skin repair itself after a long day. However, there is a third group who say that if you’re using a low percentage of vitamin C, you’re ok to use that in your AM routine, whereas, if you’re using a higher percentage, it’s better to add that to your PM routine.

As you can see, there are tonnes of vitamin C products out there. If you are confused by the options available, it is always best to chat to a practitioner who is super up on their skin game. They can guide and advise you to find the best vitamin C product that works for you, getting the glowing skin you dream of!

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