A Guide to Using Vitamin C Serums: When to Apply and Skincare Tips
Written by: Radhika Sen
Updated on: 30th September 2025
From brightening dull complexions to defending against environmental stressors, vitamin C is one of the most searched-for skincare ingredients today — and for good reason. As a gold-standard antioxidant, it’s a daily essential for anyone looking to target uneven tone, boost radiance, and support long-term skin health.
In this guide, we’ll walk you through the best time to apply vitamin C, how to layer it effectively with other products, and the key dos and don’ts to maximise its benefits. Whether you’re new to vitamin C or refining your current routine, consider this your go-to resource for getting the most from this powerhouse ingredient.
The staple antioxidant your morning routine can’t go without
Vitamin C is a skincare essential, especially in the morning. As a powerful antioxidant, it helps neutralise free radicals triggered by UV rays and pollution, while supporting collagen production and visibly brightening uneven tone. Perfect for city living, vitamin C enhances your skin’s defence system and even boosts the effectiveness of your daily sunscreen.
Why use vitamin C in a serum form?
Lightweight and fast-absorbing, serums offer an optimal delivery system for potent actives, making them ideal for infusing the skin with high-strength vitamin C. Their fluid texture suits all skin types, delivering targeted benefits without leaving residue. Compared to creams or masks, serums often provide superior stability and concentration, helping to brighten, smooth and protect skin more effectively with every use.
How to use a vitamin C serum
With today’s multi-step routines, it’s easy to feel unsure about when and how to layer your skincare correctly. A well-sequenced application not only enhances results but also supports skin health over time. Follow this simple step-by-step guide to make the most of your vitamin C serum each morning.
Step One:
Deeply cleanse your skin
Start with a gentle, pH-balanced cleanser to lift away overnight oil, sweat and impurities. Rinse with lukewarm water and lightly pat your skin dry with a clean towel, no harsh rubbing, to help preserve your skin’s natural barrier.
Gentle Cleanse is an ultra-soft, pH-balanced foaming cleanser that effortlessly removes impurities while maintaining skin’s natural moisture balance.
Step Two:
Prep with a toner (optional)
A non-exfoliating toner can help rehydrate and rebalance post-cleanse. Steer clear of strong exfoliating toners in the morning, especially before applying vitamin C, as this can increase the risk of irritation.
Daily Refresh Balancing Toner is a hydrating skin conditioner that leaves the complexion calm, conditioned, rebalanced, and ready to absorb the rest of your skincare regime.
Step Three:
Apply your chosen vitamin C serum
Dispense a few drops onto clean fingertips and gently smooth over the face and neck, ensuring even coverage. Avoid letting the pipette touch your skin; this keeps the formula fresh and contamination-free.
Explore our range of vitamin C serums.
Step Four:
Seal in the benefits with a moisturiser
Follow with a hydrating moisturiser to lock in your vitamin C and provide added comfort and nourishment throughout the day.
Step Five:
Protect with sunscreen (AM)
Finish with broad-spectrum sunscreen. While vitamin C offers antioxidant defence against daily aggressors, it’s not a substitute for SPF; both work together to support brighter, well-protected skin.
Our C-Tetra range pairs perfectly with Advanced Day Ultimate Protect.
How much vitamin C serum should you use?
Use 2–3 drops or a full dropper of your vitamin C serum, depending on the formula’s concentration. Smooth evenly across the face, neck and décolletage – extending application helps maximise benefits and supports skin health beyond just the face.
When to apply vitamin C serums?
Vitamin C serums can be used both day and night, but at Medik8, we recommend applying them in the morning. That’s because vitamin C offers daily antioxidant protection against environmental stressors like pollution and UV, making it ideal for AM use. In line with our CSA PhilosophyⓇ, vitamin A takes the lead at night.
Most skin types can tolerate daily use of vitamin C, but if you're new or have sensitive skin, start 2–3 times a week and build up gradually as your skin adapts.
Vitamin C application tips
To get the most from your vitamin C serum, follow these expert tips and avoid common mistakes that can compromise results:
Do:
✓ Use at the same time each day for consistency
✓ Apply daily for visible results
✓ Store in a cool, dark place away from sunlight
✓ Pair with supporting ingredients like vitamin E or hyaluronic acid
✓ Patch test if you have sensitive skin
✓ Start slow and build up usage
✓ Choose products tailored to your specific skin concern
✓ Always follow with SPF in the morning
Don't:
✓ Layer with strong exfoliants like AHAs or BHAs in the morning
✓ Use vitamin C after invasive skin treatments
✓ Buy products stored in clear bottles
✓ Ignore colour changes – darkening can indicate oxidation
Choosing the right vitamin C serum
Form and concentration
Look for stabilised forms of vitamin C such as tetrahexyldecyl ascorbate (THD), ascorbyl glucoside, or L-ascorbic acid. These offer antioxidant power without the irritation often linked to unstable versions. For beginners or sensitive skin types, lower concentrations (around 10%) are ideal, while more experienced users may benefit from higher strengths.
Packaging considerations
Vitamin C degrades with air and light exposure, so opt for air-tight, UV-resistant packaging to maintain potency.
Formulation synergy
Effective vitamin C serums are paired with antioxidants (like vitamin E or ferulic acid) and hydrating actives like hyaluronic acid. Avoid formulas with unnecessary fragrances or filler ingredients.
Skin concerns
Choose a serum tailored to your skin type and primary goal, whether it's brightening, smoothing or fading dark spots. Each Medik8 vitamin C serum is expertly formulated to target specific skin concerns, from gentle radiance-boosting to nourishing hydration, or age-defying antioxidant power. With advanced delivery systems designed to maximise results and minimise irritation, there’s a vitamin C solution for every skin type and goal.
Finding the best vitamin C serum for the face
Finding the right vitamin C serum starts with understanding your skin’s needs. Some forms, like THDC, offer excellent stability and suitability for most skin types. Medik8’s C-Tetra range is designed with this in mind—delivering powerful yet gentle antioxidant protection. With multiple strength options, it’s easy to start low and gradually build your skin’s tolerance for long-term results.
Our latest innovation, C-Tetra Advanced, features a high-strength 20% THDC formula for powerful results, with 0% barrier disruption*. It goes even further with barrier-boosting phyto exosomes and super-antioxidant acetyl zingerone for next-gen skin support.
*Proven via independent clinical study conducted over 4 weeks on 32 participants.
When to expect results
Vitamin C is a powerful skincare active, but like all good things, visible results take time and consistency. Here’s what you can typically expect:
Within 1–2 weeks:
Improved luminosity
☆ Boosted radiance and a more luminous complexion.
☆ Brightened, plump, and smoother skin.
☆ Strengthened skin barrier.
☆ C-Tetra Advanced: Clinically proven to brighten and visibly improve wrinkles in just 7 days.*
☆ C-Tetra: Restores the look of radiance in 7 days.**
*Proven via independent clinical study conducted over 4 weeks on 32 participants.
**Proven via independent consumer study conducted over 4 weeks on 52 participants with sensitive skin.
Within 4–6 weeks:
Reduced fine lines, even tone and smoother texture
☆ Smoother skin texture and visibly reduced fine lines.
☆ C-Tetra Luxe: Clinically proven to reduce the appearance of wrinkles and hyperpigmentation in 4 weeks.*
☆ Super C Ferulic: Clinically proven to target 4 visible signs of sun-induced ageing, including wrinkles, dark spots and uneven tone.**
*Proven via independent clinical study on C-Tetra Luxe conducted over 4 weeks on 36 participants.
**Proven via independent clinical study conducted over 12 weeks on 32 participants of all skin types and tones.
After 3 months and beyond
☆ More even skin tone, diminished pigmentation, and firmer-looking skin.
Consistency is key. With our stabilised formulas and varying strengths, you can trust your results will build over time, with minimal irritation and maximum glow.
Upgrade your skin with vitamin C
Vitamin C remains a gold-standard ingredient for brighter, smoother, and visibly healthier skin. When used correctly, it’s both safe and highly effective, especially when paired with daily SPF and vitamin A at night, as part of Medik8’s clinically proven CSA PhilosophyⓇ.
Whether you’re just starting out or looking to level up your routine, our vitamin C range – from stabilised L-ascorbic acid to next-generation formulas with ferulic acid – has the perfect match for your skin. Discover your perfect vitamin C match today.
FAQ's
Once a day is typically enough to see results. Medik8 recommends applying vitamin C in the morning as part of your daily routine, where it works best to defend the skin against environmental stressors throughout the day.
Fresh vitamin C serums are usually clear to pale yellow. If your serum has turned dark orange or brown, it may have oxidised and lost efficacy, a sign it’s time to replace it.
Vitamin C serums generally absorb within a few minutes. Once fully absorbed, you can layer your moisturiser and SPF. A properly formulated serum should not feel sticky or sit on the skin’s surface.
Yes – daily use delivers the best results. If you’re new to vitamin C or have sensitive skin, start by using it a few times a week and gradually build up to daily application.
You can apply it carefully around the eye area, but it’s best to use a dedicated vitamin C eye cream like C-Tetra Eye, which is specifically formulated to be gentle yet effective for this delicate zone.
Apply vitamin C to clean, dry skin for optimal absorption. Avoid applying directly onto damp skin, which can affect how the active ingredient is delivered and tolerated.
While vitamin C provides antioxidant protection, it’s not a substitute for sunscreen. Without SPF, your skin remains vulnerable to UV damage, which can undo the benefits of vitamin C.
Yes, although it’s most beneficial in the morning to neutralise daily environmental damage. Medik8 recommends vitamin C in the morning, followed by vitamin A at night – as part of our clinically proven CSA Philosophy.
Skipping moisturiser can reduce your skin’s hydration and barrier protection. Moisturiser helps seal in the serum’s benefits and supports healthy skin function throughout the day.
Avoid layering vitamin C with strong exfoliating acids (like AHAs/BHAs) at the same time, especially in the morning. These combinations may increase irritation. However, Medik8 products are thoughtfully formulated to be compatible when used together, meaning our exfoliating toners are gentle enough to be used alongside our vitamin C serums.
Yes, vitamin C helps defend against sun-induced free radicals. Just be sure to follow with a high-protection, broad-spectrum SPF, like Advanced Day Ultimate Protect, for full environmental defence.
Radhika Sen
Radhika Sen is a skincare enthusiast and beauty writer. She's always on the lookout for a stellar serum and moisturiser combination, topped by a sunscreen that protects and primes. Her idea of self care is to pop on a face mask, light a scented candle and call it an early night.