What is Vitamin C?

Vitamin C - also known as ascorbic acid - is a naturally occurring antioxidant found in many fruits and vegetables. While your body relies on Vitamin C for countless processes, including immune function and collagen production, your skin can't store or produce it on its own. That means it needs to come from your skincare routine.

In skincare, Vitamin C works on two levels. First, it acts as a powerful antioxidant, neutralising free radicals - unstable molecules generated by UV exposure, pollution, and stress - before they can damage your skin cells. Second, it actively intervenes in the skin's pigmentation process, inhibiting the enzyme (tyrosinase) responsible for producing melanin. The result: brighter, more even skin tone over consistent use.

But not all Vitamin C is created equal.

The Different Forms of Vitamin C

The most potent form, L-Ascorbic Acid, is also the most unstable. It oxidises quickly when exposed to air and light, turning products yellow and reducing efficacy before they even reach your skin. It's also the most likely to cause irritation, particularly in higher concentrations.

That's why The INKEY List's 15% Vitamin C + EGF Serum uses Ascorbyl Glucoside - a stabilised derivative of Vitamin C that remains effective throughout its shelf life, converts to active Vitamin C on contact with your skin, and is significantly gentler, making it suitable for all skin types including sensitive skin.

Our Vitamin B, C & E Moisturiser uses Sodium Ascorbyl Phosphate - a gentle, stable form of Vitamin C that sits perfectly in a moisturiser formula, adding a layer of daily brightening on top of your serum treatment.

Not sure which is right for you? Our 15% Vitamin C + EGF Serum uses Ascorbyl Glucoside, and our Vitamin B, C and E Moisturiser uses Sodium Ascorbyl Phosphate. Both are stable, both are gentle. The serum treats, the moisturiser maintains.

Brightens Dull Skin

Dullness happens when dead skin cells accumulate on the surface and your skin's natural renewal cycle slows down. Vitamin C accelerates this process by suppressing excess melanin production, giving you clearer, more luminous skin over time.

In an independent 4-week consumer trial of 64 participants, 87% agreed that their skin looked brighter after using our 15% Vitamin C + EGF Serum. That's not a subtle improvement - that's visible, photograph-it-worthy brightness that builds with consistent use.

Fades Dark Spots & Hyperpigmentation

Dark spots, post-blemish marks, sun damage, and uneven patches all share the same root cause: excess melanin in localised areas of the skin. Vitamin C inhibits tyrosinase - the enzyme that triggers melanin production - reducing pigmentation at source rather than just masking it.

With continued use, existing dark spots fade and new ones are less likely to form. 88% of participants in our 4-week trial saw visible improvement in skin tone and texture. The key word is consistent - this isn't a one-week ingredient. Give it 4–8 weeks and watch the transformation.

Antioxidant Protection Against Environmental Damage

Every day, your skin faces a barrage of free radicals - unstable molecules produced by UV radiation, pollution, blue light, and oxidative stress. Left unchecked, these free radicals break down collagen, cause inflammation, and accelerate the visible signs of ageing.

Vitamin C neutralises free radicals before they can cause damage, making it one of the most valuable protective ingredients you can apply every morning. Think of it as a daily antioxidant shield - invisible protection that works silently all day.

This is why we recommend using our 15% Vitamin C & EGF Serum in the morning. Layering it beneath your SPF gives your skin a dual-defence system against the environmental aggressors it faces throughout the day.

Supports Skin Firmness & Elasticity

Vitamin C plays a direct role in collagen synthesis - it's essential for the production of the proteins that keep your skin firm, plump, and youthful-looking. As collagen production naturally slows with age, maintaining a consistent Vitamin C routine helps support your skin's structural integrity.

Our hero 15% Vitamin C + EGF Serum takes this a step further with 1% Epitensive™ EGF - a plant-derived Epidermal Growth Factor from biotechnology brand Lipotrue. EGF is a naturally occurring protein that signals skin cells to renew and regenerate, supporting elasticity and helping skin look and feel firmer over time. 84% of participants in our trial agreed their skin looked healthier and less dull after just four weeks.

Is Vitamin C Suitable for Sensitive Skin?

Yes, if you pick the right form. Most stinging and redness people blame on Vitamin C comes from high-strength L-Ascorbic Acid, which needs a low pH to work and can be harsh on skin that isn't used to it.

Ascorbyl Glucoside doesn't have that problem. It stays stable in the bottle and converts once it's absorbed, so you get the brightening without the sting. Our 15% Vitamin C + EGF Serum is fragrance-free, dermatologically tested and suitable for sensitive skin, pregnancy and breastfeeding.

If you've reacted to Vitamin C before, read our full guide to using Vitamin C on sensitive skin.

Vitamin C for Dark Spots and Post-Blemish Marks 

Dark spots, sun damage and the marks left behind after a breakout all come from the same thing: excess melanin in one area. Vitamin C slows melanin production at the source rather than covering it up.

For stubborn pigmentation, pairing Vitamin C with Tranexamic Acid works better than either on its own, because they interrupt different parts of the same process. Our Tranexamic Acid Serum is £16 and layers cleanly underneath.

Sunscreen matters here too. Without it, UV keeps re-triggering the pigmentation you're trying to fade. Here's why SPF is non-negotiable for hyperpigmentation.

Our 15% Vitamin C + EGF Serum is

Fragrance-free

Consumer trial tested (4-week independent consumer trial of 64 participants)

Suitable for sensitive skin

Pregnancy & breastfeeding safe

Certified vegan

Cruelty free

Step-by-Step: Morning Application (Recommended)

1. Cleanse - Start with a clean face. Remove any overnight products.
2. Apply 15% Vitamin C + EGF Serum - Dispense a pea-sized amount onto fingertips and gently press into damp skin. Work outward from the centre of your face.
3. Wait 60 seconds - Allow the serum to absorb fully before the next step. This prevents pilling and maximises efficacy.
4. Layer additional serums if needed - Apply any other serums thinnest to thickest consistency.
5. Apply Vitamin B, C & E Moisturiser - A pea-sized amount across the face and neck to lock in the treatment and boost hydration.
6. Finish with SPF 30+ - Non-negotiable. SPF completes your antioxidant defence and protects the brightening results you're building.

💡 INKEY Tip: Apply to damp skin - not soaking wet, just slightly damp after cleansing. It aids absorption and reduces any chance of sensitivity

Step-by-Step: Evening Application (Optional)

If you choose to use Vitamin C in the evening too, the same application order applies. However, do not use Vitamin C in the same routine as retinol or AHAs/BHAs. Alternate them - Vitamin C in the morning, retinol or acids in the evening.

Morning vs. Evening: Which Is Better?

Morning is the most common choice, but it isn't a rule. Here's when to use Vitamin C depending on the rest of your routine.

How Much to Use

Vitamin C + EGF Serum: A pea-sized amount is sufficient. More does not mean better results - it can lead to pilling and waste.

Vitamin B, C & E Moisturiser: A pea-sized amount for the face. Slightly more if extending to the neck and décolletage.

How Often?

Once daily, consistently, gives the best results. Most people start to notice a visible difference in brightness within 2–4 weeks, with the most significant changes in dark spots and tone appearing at 6–8 weeks.

New to it? Start with our Vitamin C routine for beginners.

Vitamin C vs Niacinamide

Both ingredients brighten skin, but through different pathways - which is why they work beautifully together.

• Vitamin C targets pigmentation directly, inhibiting melanin production and fading existing dark spots
• Niacinamide (Vitamin B3) regulates oil production, reduces redness, and strengthens the skin barrier

Safe to use together? Yes, with INKEY's Ascorbyl Glucoside form of Vitamin C, there's no risk of the niacin flush reaction sometimes associated with mixing L-Ascorbic Acid and Niacinamide. Layer Niacinamide after your Vitamin C serum, or use one AM and one PM.

INKEY recommendation: Use the 15% Vitamin C + EGF Serum in the morning, and the Vitamin B, C & E Moisturiser brings the Niacinamide boost into the same routine seamlessly.

Here's what actually happens when you use Niacinamide and Vitamin C together, and our Niacinamide guide covers the ingredient in full.

Vitamin C vs Retinol

Two of skincare's most powerful actives - but they play very different roles.

•    Vitamin C is your morning brightener and antioxidant protector. Use morning only with results showing 2-4 weeks for brightness. Suitable for all skin types

•    Retinol is your evening cell-turnover and anti-ageing powerhouse. Use in the evening only with results showing 6-12 weeks for anti ageing. Suitable for most skin types (introduce gradually)

Safe to use together? Yes, just not in the same routine. Use Vitamin C in the AM and retinol in the PM, always following retinol with a good moisturiser.

Both are active, so timing matters. Can you use Vitamin C and Retinol together? walks through it, and our Retinol guide has the detail.

Vitamin C vs Tranexamic Acid

Both tackle hyperpigmentation - but they interrupt different parts of the pigmentation pathway.

• Vitamin C inhibits tyrosinase to reduce melanin production
• Tranexamic Acid disrupts the signal between UV exposure and melanin formation

Used together, they create a more comprehensive approach to tackling dark spots. Alternate them (Vitamin C AM, Tranexamic Acid PM) or pair Tranexamic Acid serum under your Vitamin C serum in the morning.

These work well together on pigmentation. Our Tranexamic Acid Serum is £16 — see the Tranexamic Acid guide for how it works.

Vitamin C Ingredient Compatibility Guide

Hyaluronic Acid is one of the easiest pairings. Full guide here, and more on the ingredient on our Hyaluronic Acid pillar.

Vitamin C is not a substitute for sunscreen — it works alongside it. Vitamin C and SPF: why you always need both. Our Dewy Sunscreen SPF 30 is £15.

15% Vitamin C + EGF Serum - £15 | 30ml

Our Hero Brightener

This is your daily brightening treatment. Formulated at 15% Ascorbyl Glucoside - the sweet spot for clinically meaningful results without the irritation risk of L-Ascorbic Acid - and supercharged with 1% Epitensive™ EGF, a plant-derived Epidermal Growth Factor that supports skin renewal and elasticity.

The formula:

• 15% Ascorbyl Glucoside - stabilised Vitamin C that converts to active form on contact with skin. Targets melanin production, fades dark spots, and delivers antioxidant protection
• 1% Epitensive™ EGF - plant-derived Epidermal Growth Factor by Lipotrue. Supports skin cell renewal and regeneration, boosting firmness and elasticity over time
• Lightweight, fast-absorbing texture - absorbs quickly without tackiness or greasiness

Consumer test results (4-week independent consumer trial, 64 participants):

• 87% agree skin looks brighter
• 88% saw visible improvement in tone and texture
• 84% agree skin looks healthier and less dull

What it targets:

• Dark spots and post-blemish marks
• Dull, tired-looking skin
• Uneven skin tone
• Loss of radiance
• Early signs of ageing

Suitable for: All skin types | Sensitive skin | Pregnancy & breastfeeding | All ages

Certifications: Vegan Society Certified | Leaping Bunny Cruelty-Free | Fragrance-Free | Consumer Trial Tested

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Vitamin B, C & E Moisturiser - £9 | 50ml

Complete Your Brightening Routine

Your daily moisturiser and Vitamin C aren't separate steps - with this formula, they work together. The Vitamin B, C & E Moisturiser layers three skin-brightening vitamins into a lightweight, non-greasy formula that seals in your serum treatment and maintains your radiance all day.

The formula:

• Vitamin B3 (Niacinamide) - balances oil production, reduces redness, and brightens
• Vitamin C (Sodium Ascorbyl Phosphate) - a stable, gentle form of Vitamin C for daily brightening maintenance
• Vitamin E (Tocopheryl Acetate + Tocopherol) - antioxidant-rich, soothing, and smoothing
• 1% Coconut Oil - softens skin without heaviness

Why use it with the serum?

The serum does the active treatment work at a higher concentration. The moisturiser maintains and supports your daily radiance with a gentler, sustained dose of the same brightening vitamins - extending the benefits of your serum across the entire day.

Suitable for: All skin types | AM & PM use | Daily use

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The Form of Vitamin C Matters More Than the Percentage

Before you get fixated on concentration numbers, understand the form. A 20% L-Ascorbic Acid serum that's oxidised in your bathroom cabinet is delivering zero results. A stable 15% Ascorbyl Glucoside serum that maintains its efficacy from first use to last pump? That's where results come from.

Supporting Ingredients to Look For

The best Vitamin C formulas don't work in isolation. Look for:

• EGF (Epidermal Growth Factor) - supports skin renewal and elasticity alongside brightening
• Hyaluronic Acid - maintains hydration while Vitamin C targets pigmentation
• Niacinamide - works alongside Vitamin C for oil control and brightness
• Vitamin E - a natural antioxidant partner that stabilises Vitamin C in formulas

Serum vs Moisturiser: Which Do You Need?

Is Vitamin C Safe?

Yes, Vitamin C is one of the most widely studied and well-tolerated ingredients in skincare. When formulated correctly (in a stable form, at an appropriate concentration, and at the right pH), it causes very few issues for the vast majority of skin types.

INKEY's choice of Ascorbyl Glucoside specifically removes the most common pain points associated with Vitamin C: the instability, the oxidation, and the irritation potential.

Potential Side Effects

Colour change: You may notice your serum taking on a slightly yellow or amber tint over time. This is natural oxidation - it does not affect the safety or performance of the product.

Mild sensitivity: Unlikely with Ascorbyl Glucoside, but if you're new to actives, introduce gradually. Start every other morning, building to daily use over 1–2 weeks.

Layering reactions: Using Vitamin C in the same routine as retinol or strong AHAs can cause irritation. Keep them in separate AM/PM routines.

Who Should Take Care?

• Compromised skin barrier? Introduce Vitamin C gradually - once every other day - and always patch test first
• Using prescription retinoids? Check with your GP or dermatologist before adding strong actives to your routine
• Very sensitive or reactive skin? Start with the Vitamin B, C & E Moisturiser as a gentler introduction before adding the serum

Vitamin C & SPF, Non-Negotiable

Using Vitamin C without SPF is like building a sandcastle at low tide. Vitamin C increases your skin's sensitivity to UV damage, which means skipping SPF actively undermines the brightening results you're working towards. Always finish your morning Vitamin C routine with SPF 30 or higher.

💡 INKEY Tip: Patch test every new product before adding it to your full routine. Apply a small amount to the inside of your wrist or behind your ear for 24 hours before using on your face.

Worried about breakouts? Can Vitamin C cause breakouts? covers what's really going on.

If your serum turns yellow or darkens, that's oxidation. How to store your Vitamin C serum explains how to slow it down.

Application Technique

• Apply to skin that's slightly damp - not dripping wet, not fully dry
• Use your fingertips, not palms - you lose less product
• Pat, don't rub - pressing the serum into skin is more effective than rubbing it across the surface
• Pea-sized amount - resist the urge to over-apply

Common Mistakes to Avoid

• Skipping SPF after morning use - your results depend on it
• Mixing Vitamin C with retinol in the same routine - use AM/PM instead
• Expecting instant results - consistency over 4–8 weeks is where the transformation happens
• Storing in direct sunlight or a warm bathroom - keep your Vitamin C serum in a cool, dark place to maintain its stability
• Applying to dry skin straight from the shower - slightly damp skin aids absorption

Pro Layering Order (Full AM Routine)

How Long Until You See Results?

Why We Chose Ascorbyl Glucoside

Formulators face a fundamental challenge with Vitamin C: the most active form (L-Ascorbic Acid) is notoriously unstable. It requires a low pH environment to remain effective, and even then, it oxidises rapidly on exposure to air and light - often turning products yellow and reducing their efficacy within weeks of opening.

Ascorbyl Glucoside solves this. It's a glycoside form of Vitamin C - Vitamin C bonded to glucose - which creates a stable molecule that maintains its efficacy throughout its shelf life. When applied to skin, skin enzymes cleave the glucose molecule, releasing active L-Ascorbic Acid directly at the skin surface. You get the full brightening power of Vitamin C, in a formula that stays effective from first use to last.

Why We Added Epitensive™ EGF

EGF (Epidermal Growth Factor) is a naturally occurring protein in the body that plays a key role in cell signalling, specifically triggering skin cells to renew and regenerate. Our 1% Epitensive™ is a plant-derived EGF from biotechnology company Lipotrue, making it suitable for vegans and more sustainably sourced than animal-derived alternatives.

In clinical studies by Lipotrue, Epitensive™ has been shown to support skin elasticity and promote cell renewal - making it the ideal partner ingredient for Vitamin C's brightening activity. While Vitamin C fades what's already there, EGF encourages the generation of new, healthier skin cells beneath.

EGF is the less familiar half of this formula. What is EGF and what does it do in skincare?

Our Quality Standards

Every INKEY List product is held to the same standards:

Dermatologically tested

Fragrance-free

Vegan Society Certified

Leaping Bunny Certified

100% Recyclable Packaging

Pregnancy-safe

The Gold Standard Morning Routine

Evening Routine (Vitamin C Optional)

Power Combinations

Vitamin C isn't just a trend - it's one of the most clinically validated brightening ingredients in modern skincare, with decades of research behind it and real results that build with every application. Whether you're just starting your active skincare journey or adding a targeted brightening step to an existing routine, making Vitamin C your daily morning habit is one of the highest-return decisions you can make for your skin.

Start with the 15% Vitamin C + EGF Serum at £15 - a consumer tested, gentle, stable formula that delivers real visible brightness without the irritation, without the guesswork, and without the price tag you'd expect.

Apply every morning. Layer with SPF. Be consistent. Watch what happens.

Shop Vitamin C Collection

• What is Hyperpigmentation?
• What is Niacinamide?
• What is Retinol?
• What is Hyaluronic Acid?
• What is Tranexamic Acid?
• What is SPF?
• The Complete Skincare Guide