Vitamin C serum has become one of those skincare recommendations you hear everywhere. Dermatologists recommend it. Beauty editors swear by it. Your favourite skincare obsessive probably has one permanently parked next to the bathroom mirror.But what does vitamin C serum actually do?

The answer is more interesting than simply “it makes your skin glow”. Vitamin C is a powerful antioxidant that can help protect skin from environmental stress, support collagen production and improve the appearance of pigmentation and uneven tone. Used consistently, a well-formulated vitamin C serum can be one of the most useful additions to a morning skincare routine.

The catch? Not all vitamin C serums are created equal. The form of vitamin C, its concentration, the supporting ingredients and even the bottle it comes in can all affect how well it performs. So whether you are completely new to vitamin C serum or wondering if your current one is actually doing anything, here’s what you need to know.

If you’re ready to browse, start with our vitamin C serum collection.

Vitamin C is best known as an antioxidant. In simple terms, antioxidants help neutralise free radicals: unstable molecules generated by factors such as UV exposure and pollution that can contribute to oxidative stress and premature skin ageing. But antioxidant protection is only part of the story....

If your complexion is looking a little flat, tired or generally lacking its usual luminosity, vitamin C can help.

Vitamin C supports a brighter, more even-looking complexion and can help reduce the appearance of pigmentation over time. It works in part by influencing melanin production, helping to address the uneven distribution of pigment that can leave skin looking patchy or dull.

This is why vitamin C serum is particularly popular with anyone dealing with sun spots, post-inflammatory pigmentation or an uneven skin tone and while “glow” is a rather overused skincare word, in this case there is some science behind it.

It plays an important role in collagen synthesis. Collagen is one of the structural proteins responsible for the firmness and resilience of skin. As we age, collagen production naturally declines, contributing to fine lines, loss of firmness and changes in skin texture.

Using vitamin C serum won't magically replace lost collagen but topical vitamin C can support the skin's natural collagen production and help protect against some of the oxidative stress associated with premature skin ageing.

Every day, your skin is exposed to environmental stressors. UV radiation and pollution can generate free radicals that contribute to cellular damage and visible signs of ageing.

It helps neutralise these free radicals, giving skin an additional layer of antioxidant defence.

Importantly, it is not a replacement for sunscreen. Think of the two as a particularly good pairing, SPF helps protect against UV radiation, while vitamin C provides antioxidant support alongside it.

The good news is that vitamin C can work for most skin types!

It is particularly useful if your priorities are brightness, pigmentation, uneven skin tone, early signs of ageing or environmental protection. And you don't need to wait until your skin shows visible signs of ageing before introducing it.

That said, the formulation matters! L-ascorbic acid can cause dryness, redness or irritation in some people, particularly if the skin barrier is already compromised. If you have very sensitive or reactive skin, patch testing and starting with a lower concentration is sensible.

Not necessarily.

For L-ascorbic acid, concentrations around 10–20% are commonly recommended. Going higher doesn't automatically mean better results and may increase the likelihood of irritation.

The more important question is whether the vitamin C is in a well-formulated, stable product that your skin can tolerate consistently. Because the best product is ultimately the one you actually use!

Vitamin C serum is wonderfully easy to slot into a routine.

Start with clean skin. Use your usual cleansers and follow your usual routine. Gently pat your face dry.

Apply your serum after cleansing and before moisturiser and SPF. A few drops are generally enough to cover the face and neck. There's no need to drown your skin in serum in pursuit of faster results.

Follow with your usual moisturiser, if your skin needs it.

This is the important bit. Every morning, finish your routine with a broad-spectrum SPF. Vitamin C and sunscreen complement one another but vitamin C is not a sunscreen and should never be used instead of one.

You can technically use vitamin C at night, but morning application makes particular sense because antioxidant protection is useful during the day, when your skin is exposed to UV and environmental stressors. Think of vitamin C as part of your daytime defence team: cleanse, vitamin C, moisturiser, SPF.

This is where your bathroom cabinet suddenly becomes more important.

L-ascorbic acid is notoriously sensitive to light, air and heat. Exposure can cause the formula to oxidise, reducing its effectiveness. Dark or tinted packaging and well-designed airless packaging can help protect the formula.

If your vitamin C serum gradually changes from its original colour to a noticeably darker yellow, orange or brown, it may have oxidised and is best replaced.

In other words: if your vitamin C serum has started looking like orange squash, don't assume that's a sign it's working harder.

Yes, but you don't necessarily need to use them at the same time.

For most people, a straightforward way to introduce both ingredients is to use vitamin C in the morning and retinol in the evening. This keeps your routine simple and can also help reduce the chance of irritation from layering multiple active ingredients in one application. 

If you're considering using retinol, our complete guide explains how to introduce it gradually, choose the right strength and build a routine around it.

The golden rule with active skincare? More isn't always the answer.

L-ascorbic acid is the most extensively studied and one of the most potent forms of topical vitamin C. However, it is also less stable and can be more irritating for some skin types.

Vitamin C derivatives, such as tetrahexyldecyl ascorbate or ascorbyl glucoside, are often used when a formula needs greater stability or a gentler skin feel.

The right choice isn't necessarily the strongest form. It is the form that delivers meaningful benefits while working comfortably with your skin.

A big number on the front of a bottle doesn't tell you everything. Look out for the following:

• The form: Is it L-ascorbic acid or a derivative?

• The concentration: more isn't automatically better.
• The packaging: is the formula protected from light and air?
• Supporting ingredients: vitamin E and ferulic acid are commonly paired with vitamin C.
• Your skin type: sensitive skin may benefit from a gentler derivative or lower concentration.

This is one reason we prefer a carefully curated approach to skincare rather than simply chasing the highest percentage on the label.

Essence 27 by Cosmetics 27

If you're looking for a sophisticated serum that combines treatment with a more luxurious skincare experience, Essence 27 by Cosmetics 27 is one of our favourites. It sits firmly in the premium category, but this is a formula designed for people who want more from their vitamin C than a basic brightening step.

Time-Release Pre-Serum Drops by Wildsmith 

For something a little different, Wildsmith Time-Release Pre-Serum Drops offers a clever approach to incorporating vitamin C into a wider skincare routine. Pre-serum means exactly that: use it as a preparatory step before your usual serum or moisturiser, depending on the rest of your routine.

Effica C Vitamin C Serum by Synergie Skin 

A rapidly absorbing, non-acidic vitamin C serum suitable for all skin types, including sensitive skin. The biocompatible formula provides gentle and targeted penetration for maximum results. Vitamin C and coenzyme Q10 work in tandem to deliver a potent dose of antioxidants, reduce the appearance of fine lines and wrinkles, promote even skin tone, reduce age spots, and protect against UV and environmental damage.