To brighten your skin and protect it against damage, a high-strength vitamin C is your ally. But how high is high and which products pack the best percentage punch? We investigate

Alongside  retinol , SPF , peptides  and ceramides , vitamin C  has claimed its place as a daily essential in skincare. What else can act as a potent antioxidant, anti-inflammatory, make  pigmentation  less visible, support collagen production and provide a base level of UV protection? It's a great ally all year round but especially in summer as it increases the effectiveness of your sunscreen and gives the skin better protection from UV rays, according to skincare expert Paula Begoun  of Paula's Choice. When combined with vitamin E the sun protection is even greater, according to a study .

Many experts agree that a high percentage of vitamin C in your serum is essential for visible results. But how high is high? "I would call anything from 10 per cent onwards high-strength," says skin expert Ingeborg Van Lotringen, author of  Great Skin: Secrets the Beauty Industry Doesn't Tell You.

What you consider a high percentage may also depend on your skin type, as aesthetician Dr Sophie Shotter explains. "Sensitive skin may only need a 5 per cent formulation, an average type skin ten to 15 per cent and an oilier skin 20 per cent. Research suggests there is no additional benefit to using higher percentages than this."

In the UK, vitamin C serums don't tend to go above 30 per cent due to EU regulations and despite Brexit, there are no murmurings at present about this changing. However, in the US, Allies of Skin sells its 35% Vitamin C+ Perfecting Serum . If you're desperate to get your hands on it you can buy it on import site Revolve  for £102, or via FaceGym in the UK but Allies of Skin tells us there are no plans for it to retail generally over here.

You should also look for an opaque bottle as exposure to sunlight can oxidise vitamin C, making it redundant. In addition look for vitamin C in the form of l-ascorbic acid. "This is the most active form of vitamin C and is the one I would look out for in the ingredients list," says Dr Sophie.

High-strength vitamin C can often tingle when you apply it, but it's not necessarily a bad thing. “Some people might sense a stinging or burning feeling, which can be alarming, especially because we know irritation is bad for skin," says Inge. However, in vitamin C's case, this is not irritation, it’s the skin adjusting to the product’s pH and the feeling should stop in a matter of minutes.

“Whether your vitamin C stings or not depends on your skin and its pH," she adds. "Some feel stinging sooner than others. I'd say you can expect some stinging from 10 per cent formulas onwards. Any stinging after five minutes, or prolonged redness or itching means you've chosen a product that's too much for your skin, and you should build it up slowly," Inge advises.

You will often find vitamin C alongside antioxidant ferulic acid which is known for decreasing fine lines and wrinkles and fading brown spots and combined with barrier-boosting vitamin E, which also helps protect against photodamage when combined with vitamin C. These complementing antioxidants pair perfectly with vitamin C and boost its efficacy and stability.

Here are our picks of the best the high strength vitamin C serums and boosters for every skin type

For oily skin: SkinCeuticals Silymarin CF, £145 for 30ml

SkinCeuticals launched Silymarin CF in December 2020, specifically for oily, breakout-prone skin. The price is eye-watering, but it has the high-performing ingredients to back it up, including 15 per cent l-ascorbic acid vitamin C, alongside 0.5 per cent ferulic acid for glow-boosting, plus 0.5 per cent silymarin which ups the antioxidant protection and helps limit breakouts. 0.5 per cent salicylic acid is in the mix too to gently unclog pores.

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For gentle protective power: Perricone MD Vitamin C Ester CCC+ and Ferulic Brightening Complex 20%, £129 for 59mls

As the name suggests, there are three types of vitamin C in this 20 per cent serum, as well and power players vitamin E and ferulic acid. This silky, sting-free serum has everything you could want from a vitamin C; not for nothing was it a finalist in the Skin Glow category of the Get The Gloss Beauty and Wellness Awards . Perricone MD was one of the first skincare brands to major on vitamin C many years ago and uses vitamin C ester, a highly stable and less irritating form of l-ascorbic acid. This is its most potent C and with consumer trials behind it, it is a favorite of the GTG team. Yes, it's on the pricey side but note that the 59ml pump bottle is at least twice the size of others in our edit.

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For firmer skin: Allies of Skin 20% Vitamin C Brighten + Firm Serum, £28 for 8ml

This serum has an unusual honey-like texture that feels nourishing on dried-out skin, nurturing at the same time as giving a boost of antioxidants. It includes an ethylated form of 20 per cent l-ascorbic acid vitamin C which is an extra-stable form of the ingredient, plus orange extract to boost elasticity and smoothness mixed with antioxidant glutathione to protect skin and diminish dullness. The price may seem low for this premium brand, so do note that it's a very tiny eight ml bottle.

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For improving skin texture: Paula's Choice C15 Super Booster, £36 for 20ml

Part of Paula's Choice booster range, these drops you add to your moisturiser or serum. They combine 15 per cent vitamin C l-ascorbic acid with vitamin E and ferulic acid as well as skin-smoothing peptides  to improve the skin's texture. Add two to three drops to your skincare routine and watch your glow emerge.

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For glow:  Ole Henriksen Banana Bright Vitamin C Serum, £53 for 30ml

Founder of brow brand Refy  Jess Hunt says she can't go without this zesty-scented serum, which gives her a glow so bright she's convinced it can be seen through makeup! It feels ultra-smooth on the skin (no stickiness here) and gives a real freshness to the face. It has 15 per cent l-ascorbic acid vitamin C along with five per cent PHAs  to whisk away dead skin cells for a brighter complexion. Hyaluronic acid adds dewy hydration.

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For nighttime rejuvenation: DCL C Scape High Potency Night Booster 30, £108 for 30ml

Unlike many vitamin C serums, this one has to be applied at night. At 30 per cent l-ascorbic acid it's one of the strongest in our edit, and it does sting. Trinny Woodall says that after using it at bedtime she always wakes up with a bright glow but definitely feels a tingle upon application. It supports collagen production too and promotes an even skin tone.

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For hydrated skin: Obagi Professional-C Serum 20%, £128 for 30ml

This liquid fuses 20 per cent l-ascorbic acid vitamin C with propylene glycol which helps with skin hydration. This extra quenching ingredient reduces the appearance of fine lines and wrinkles

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For HEV blue light protection:  Zenii Antioxidant Power Serum, £75 for 30ml

Founded by aesthetic doctor Johanna Ward this serum includes 20 per cent l-ascorbic acid vitamin C as well as two per cent niacinamide  to support the skin barrier, one per cent vitamin E and one per cent ferulic acid to deliver anti-ageing results and protection against UV and blue light. Dr Jo recommends using this on your hands  as well as your face to keep them looking young too.

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For even skin tone: Medki8 Super C30 Intense, £59 for 30ml

This is Medik8's most powerful vitamin C, (it used to be called Super C Ferulic) fusing 30 per cent l-ascorbic acid vitamin C, antioxidant ferulic acid, vitamin E and brightening, glow-giving turmeric  which blocks the tyrosinase enzyme which produces melanin, to help create an even skin tone. For such a high-strength vitamin C, this is a reasonable price, as we've come to expect from Medik8. It absorbs quickly so you can get on with your following skincare steps.

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For acne-scarring: Beauty Pie Superdose C C-Suite Rapid Action Power Brightener, members £11.52 for 30ml, typical price £80

This non-greasy vitamin C serum sandwiches 15 per cent sodium ascorbyl phosphate vitamin C (a water-soluble form of the ingredient) with ferulic acid and tranexamic acid to brighten dull, uneven and scarred skin. The one per cent tranexamic acid helps reduce the appearance of sun-induced pigmentation. It does have that unmistakable sort of smokey smell vitamin C sometimes has but when it has such an effect on acne scarring we can put up with that.

Not a member of Beauty Pie? Join using code GTGSENTME and get an extra £50 to spend.

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For fruit-powered brightening: Drunk Elephant C-Firma Day Serum, £67 for 30ml

Now that Drunk Elephant has landed at Boots, there are Advantage points to be had in stocking up on one of our favourite brands, including this 15 per cent l-ascorbic vitamin C serum. It also has one per cent vitamin E and 0.5 per cent ferulic acid, combined with pumpkin and pomegranate extracts to work away at dead skin cells for extra brightening.

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