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.
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:
Choosing the right vitamin C serum
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:
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.