If you have a sensitive skin type (or even if you just want to treat your skin carefully) then you might have thought vitamin C skincare was not for you. Let’s be honest, vitamin C skincare has a bad rep for being ‘stingy’, irritating and generally pretty ‘Ouchy’.
Last week we chatted about the, ‘6 Proven Benefits of Vitamin C Skincare‘ and today my friend I am going to share with you the 2 different types of vitamin C that you’re going to find in vitamin C skincare. Yup, you read that right. There’s more than just one type of vitamin C used in skincare and guess what… one of them is the key culprit for vitamin C’s ‘badass to sensitive skin types’ reputation.
The Traditional Vitamin C, L-ascorbic Acid
The first type of vitamin C we are going to chat about, gets called ‘L-ascorbic acid’. This is the ‘godfather’ of the vitamin C skincare world. L-ascorbic acid is the traditional, age old version of vitamin C, its skin benefits are very well studied as its been hanging around skincare town for a long-ass time.
L-ascorbic acid gets its name from the first skin condition it treated. ‘Back in the day’ sailors used to spend months at a time at sea and with no fridge-freezers all of their fresh fruit and veg would be gone off before they’d even reached the 2-week mark (assuming they hadn’t gobbled it in the first week, that’s probably more likely ‘eh ;)). That meant sailors had pretty limited diets. It led to a condition called scurvy which is where all the tissues in your body fall apart, skin pretty much ‘dissolves’ away. This is all because of a lack of vitamin C.
When we realised what was going on, sailors always travelled with a huge stock pile of limes and vitamin C got the name, ‘against-scurvy’ but of course in Latin ‘eh.
L-ascorbic acid is the culprit for the bad rep vitamin C has when paired up with sensitive skin. This is because…
- L-ascorbic acid is only ‘bio-active’ at low pH. pH is a ‘ruler’ for how acidic or alkaline something is, 7 is ‘on-the-fence’ and anything below that is acidic. Your skin actually has a pH all of its own, it’s between 4.2-5.5 and that slightly acidic pH is what helps to keep your skin healthy. For L-ascorbic acid to actually ‘work’ it needs to be in a skincare product which has a pH less than 3.5. That’s because vitamin ‘C’ will go off when the pH is higher and it also won’t penetrate skin.
(That low pH means that sensitive skin types can get ‘stingy’ red, irritated skin reactions exactly like when you peel an orange and have a small nick on your skin. It’s also exactly what lemon juice (which has a very low pH of around 2) will do to skin).
- L-ascorbic acid gets dosed ‘all at once’. Imagine if you tried to drink your entire daily dose of water in 10 minutes. I wonder if there’s a world record for that :). Drinking your daily allowance of water in 1 sitting is pretty extreme. You probably wouldn’t notice sipping down on your daily dose through the whole 12 hours (who am I kidding… your multi-tasking 16 hour days), but you would notice having to guzzle that all down in 10 minutes. Traditional vitamin C skincare is like metaphorically being ‘gung-dunked’ in active.
(High doses & concentrations of vitamin C are ‘too much to handle’ for sensitive skin types. It swings skin from one condition to another and your sensitive skin police get alerted).
Pro-tip: There are now newer formulations of vitamin C that work around this ‘big dose’ challenge. They coat vitamin C in little sweaters that take time to dissolve away in skin (it’s called microencapsulation) and if you see a product that has this technology, it’ll be called a ‘time-release’ formula.
Psst, if you’re serious about getting glowing, healthy skin be sure to join for my 7 days of Get Great Skin Started email lessons (you get one new Great Skin email lesson each day) so you can go from feeling like your skin’s bleugh to wow, I glow so much people keep wondering if I’m pregnant 😅. Join for free here.
A New Generation of Vitamin C, Magnesium Ascorbyl Phosphate
Magnesium ascorbyl phosphate is one version of a new generation of ‘protected’ vitamin C types. Let’s call it MAP for short. MAP is a type of vitamin C that gets around how ‘god dam quick’ a vitamin C serum can ‘go-off’. Vitamin C is so active that it likes to react before it can get onto your skin. If you’re using a vitamin C skincare product and it’s gone a bit ‘brown-ish’ that is a good sign your vitamin C has ‘gone-off’ (oxidised).
The MAP type of Vitamin C has a protective ‘side-kick’ that’s the magnesium, phosphate bit. It’s kinda like a protective sandwich, M-ascorbyl (the vitamin C bit)-P.
In cosmetic chemistry it’s literally called a ‘protecting group’ and it makes this form of vitamin C a hell of a load more stable. That means for sensitive skin types that…
- Magnesium ascorbyl phosphate can be used at ‘skin’ pH. MAP is actually stable at that neutral, ‘sat on the fence’ pH of 7. That means it can also be used in skincare at a pH that is in the same range as your skins (4.2-5.5). That avoids the ‘sting’ sensation and ‘redness’ reactions that can happen when using a low pH L-ascorbic acid skincare pick.
- Magnesium ascorbyl phosphate is ‘dosed’ more slowly. Remember MAP has that protective side-kick? Well once MAP gets absorbed into your skin, skin gradually teases that side-kick away from the active form of vitamin C. It’s a bit like those time-released versions of vitamin C that I mentioned before. It means that skin doesn’t get ‘gunged’ in active, instead there’s a slower ‘un-zipping’ of the active.
Skincare products with magnesium ascorbyl phosphate; The Ordinary’s Magnesium Ascorbyl Phosphate 10% (£7.80/30ml), Paula’s Choice, Calm redness relief moisturiser £23/60ml, Olay Total Effects 7-in-1 Anti-Ageing Night Firming Moisturiser £14.99/50ml.
The ‘Other’ Protected Skincare Versions of Vitamin C
I gave MAP its own little sub-section as I’d generally say it’s the better studied and more sensitive skin friendly version of the new generation of Vitamin C’s. There are also 6 others (and they’ll probably be new ones coming at us in the future), I’ve listed them out below with a pH indicator so you can get a snapshot of these guys’ sensitive skin skills…
(some of these are even oil soluble! The top layers of your skin are also made of oil, and actually every living cell you have is too, it’s what keeps the watery contents of a cell from spilling out. It means that an oil soluble vitamin C, is more skin-identical than L-ascorbic acid which is water soluble. When an ingredient is skin similar, or works in a similar way to your skin, there is a much smaller chance that your skin will react to it).
- Sodium ascorbyl phosphate (stable at pH7, so it can be used in skincare that’s made to match your skins pH level) – in First Aid Beauty Vitamin Hydrating Mist £10/59ml
- Tetrahexyldecyl Ascorbate (oil soluble, and when in water needs to be below pH 5) – in The Ordinary Ascorbyl Tetraisopalmitate Solution 20% in Vitamin F £15/30ml(oil only formulation!), First Aid Beauty Facial Radiance Serum £33/30ml
- Ethyl ascorbic acid (most stable at pH5-6, which is in skin’s ball park) – in Kiehl’s Clearly Corrective Dark Spot Solution £36/30ml, The Ordinary Ethylated Ascorbic Acid 15% Solution £18/30ml
- Ascorbyl Palmitate (this is a low pH bad boy, but it’s also oil soluble, so if you find this guy in a facial oil, then pH is no problem (pH only works for water, oil doesn’t have a pH) – in Palmer’s Cocoa Butter Formula Eventone Dark Spot Corrector £9.99/30ml
- Ascorbyl Glucoside (stable at pH 7, but it’s a much less studied version of vitamin C) – in Vichys, Normaderm – Anti-age, resurfacing care serum, £15.50/50ml, The Ordinary Ascorbyl Glucoside Solution 12% £9/30ml
- Ascorbyl 2-Phosphate 6-Palmitate (another stable at pH 7 winner, but also less studied)
Tell me about your experiences with vitamin C skincare… do you have sensitive skin? Have you found a hero product with one of these?

Cheryl Woodman is a scientist, skin health expert & award-winning skincare formulator who’s more friend next door than bow tie wearing professor. Through her 1-2-1 services and video courses she’s here helping you get healthier, happier skin you feel comfortable, confident and like the freakin’ awesomesauce you are in. Select the option which best describes your skin health here to see and hear the amazing transformations you could be getting.