Vitamin C Serums Explained: Which SkinCeuticals or iS Clinical Formula Suits Your Skin?
The right vitamin C serum depends on three things: your skin type, the main concern you want to address and how sensitive your skin is. SkinCeuticals and iS Clinical both make clinically formulated vitamin C serums for every skin type, from dry and sensitive to oily and breakout-prone, so the goal isn't finding the "best" serum, it's finding the one that suits you.
If you've ever stood in front of a shelf of premium serums wondering which one is worth the investment, this guide is for you. Below, I'll walk you through how I match vitamin C to my clients' skin in the clinic, so you can choose with confidence.
Key takeaways
Choose a vitamin C serum based on your skin type and main concern, not trends or reviews.
Dry and sensitive skin often suits SkinCeuticals C E Ferulic, while oily and blemish-prone skin often suits SkinCeuticals Silymarin CF.
Sensitised, redness-prone or recently treated skin often suits iS Clinical Pro-Heal Serum Advance+.
Apply vitamin C in the morning after cleansing, then follow with moisturiser and sunscreen.
Vitamin C works alongside daily SPF, it doesn't replace it.
What does a Vitamin C serum actually do for your skin?
A vitamin C serum is a concentrated antioxidant treatment designed to help defend your skin against everyday environmental stressors like UV exposure and pollution. These stressors create free radicals, unstable molecules that contribute to visible signs of ageing such as dullness, uneven tone and fine lines.
Vitamin C also plays a role in your skin's natural collagen production and is known for supporting a brighter, more even-looking complexion. That's why it's one of the most recommended ingredients in any skin professional's toolkit, and why it's often the first serum I suggest adding to a routine.
Why clinic-grade Vitamin C is different
Not all vitamin C serums are created equal. The difference between a clinic-grade formula and a budget serum comes down to four things.
| What to look for | Why it matters |
|---|---|
| The form of vitamin C | L-ascorbic acid is the most researched form of vitamin C in skincare |
| Concentration | Clinical formulas use a considered, tested percentage rather than a token amount |
| Supporting antioxidants | Ingredients like vitamin E and ferulic acid help vitamin C stay stable and work harder |
| Formulation and packaging | Vitamin C is fragile, so clinical brands formulate for stability and protect it from light and air |
For example, SkinCeuticals C E Ferulic combines 15% L-ascorbic acid with 1% vitamin E and 0.5% ferulic acid, a formula the brand has built its reputation on. iS Clinical's GeneXC Serum contains 20% vitamin C alongside its signature Extremozymes.
“A lot of clients come to me having already spent money on vitamin C serums that didn’t do much for them. Usually it’s not that vitamin C doesn’t work for their skin, it’s that the formula wasn’t right for them.”
How to choose the right Vitamin C serum for your skin
When I recommend a vitamin C serum in clinic, I work through these four questions:
What's your skin type? Dry, normal, combination or oily skin all respond best to different textures and supporting ingredients.
What's your main concern? Dullness, uneven tone, fine lines or breakouts will guide which formula I reach for.
How sensitive is your skin? Reactive or redness-prone skin needs a gentler, more calming approach.
Are you having in-clinic treatments? Skin that's recovering from a treatment has different needs to skin that isn't.
“I never give every client the same vitamin C. Two people can have the same concern, like pigmentation, but if one has oily skin and the other has sensitive skin, I’ll recommend completely different serums.”
The SkinCeuticals Vitamin C Serums
SkinCeuticals C E Ferulic
Best suited to dry and sensitive skin, and visible signs of ageing. C E Ferulic is SkinCeuticals' signature daytime antioxidant serum, combining 15% pure vitamin C with vitamin E and ferulic acid. It's designed to help defend against environmental damage while supporting firmer, brighter-looking skin, making it a beautiful everyday foundation for anyone focused on healthy ageing.
“C E Ferulic is my go-to for clients who want one hardworking antioxidant serum to anchor their morning routine.”
SkinCeuticals Phloretin CF Gel
Best suited to normal, combination and sensitive skin, and uneven skin tone. Phloretin CF Gel pairs vitamin C with phloretin and ferulic acid, three antioxidants working together with a focus on discolouration and uneven tone. Its lightweight gel texture absorbs quickly, making it a lovely option if you find richer serums feel heavy on your skin.
SkinCeuticals Silymarin CF
Best suited to oily and blemish-prone skin. Silymarin CF combines vitamin C with milk thistle extract and salicylic acid. It's designed to help prevent the oxidation of oil on the skin, which can contribute to breakouts, while gently exfoliating. If you've avoided vitamin C because other serums felt too rich, this is the formula I'd point you towards.
iS Clinical Vitamin C Serums
iS Clinical Pro-Heal Serum Advance+
Best suited to sensitised, redness-prone and blemish-prone skin, and skin recovering from treatments. Pro-Heal Serum Advance+ combines L-ascorbic acid with vitamin E, vitamin A and olive leaf extract. It's formulated to calm and support compromised skin, which makes it one of the most versatile serums on my shelf.
“Pro-Heal is my go-to recommendation after almost any in-clinic treatment, whether that’s laser, Alma Harmony, microneedling or a chemical peel. I also recommend it for anyone with rosacea, as it’s calming without being aggressive.”
iS Clinical Super Serum Advance+
Best suited to most skin types, and fine lines, uneven tone and the appearance of scarring. Super Serum Advance+ pairs 15% L-ascorbic acid with copper tripeptide-1, centella asiatica and hyaluronic acid. It's designed to support smoother, more even-looking skin while delivering antioxidant protection, making it a strong multitasker for clients targeting texture as well as tone.
iS Clinical GeneXC Serum
Best suited to mature skin, dullness and visible signs of ageing. GeneXC Serum contains 20% vitamin C alongside Extremozymes, superoxide dismutase and botanical antioxidants. It's designed to help brighten, support elasticity and protect against the visible signs of ageing, ideal if you want a potent antioxidant for more mature skin.
For the delicate eye area, C Eye Serum Advance+ brings vitamin C into a formula designed specifically for the skin around your eyes.
Which Vitamin C Serum suits your skin?
Find your skin type in the "Best suited to" column to see where to start.
| Serum | Brand | Best suited to | Skin concerns it supports | Texture |
|---|---|---|---|---|
| C E Ferulic | SkinCeuticals | Dry and sensitive skin | Visible ageing, dullness | Lightweight serum |
| Phloretin CF Gel | SkinCeuticals | Normal, combination and sensitive skin | Uneven tone, discolouration | Lightweight gel |
| Silymarin CF | SkinCeuticals | Oily and blemish-prone skin | Oiliness, breakouts | Lightweight serum |
| Pro-Heal Serum Advance+ | iS Clinical | Sensitised and redness-prone skin | Redness, breakouts, post-treatment recovery | Lightweight serum |
| Super Serum Advance+ | iS Clinical | Most skin types | Fine lines, uneven tone, scarring | Lightweight serum |
| GeneXC Serum | iS Clinical | Mature skin | Dullness, visible ageing | Lightweight serum |
How to use Vitamin C Serum in your routine
For most people, vitamin C works best in the morning, giving your skin antioxidant support throughout the day. Here's the order I recommend:
Cleanse and gently pat your skin dry.
Apply your vitamin C serum to dry skin across your face and neck.
Follow with your moisturiser.
Finish with a broad-spectrum sunscreen, such as SkinCeuticals Ultra Facial Defense SPF50 or iS Clinical Eclipse SPF 50+.
Vitamin C and sunscreen work as a team, but vitamin C is not a replacement for SPF. As the UV index climbs heading into an Australian summer, daily sunscreen is non-negotiable, and vitamin C is a supporting layer underneath it.
To keep your serum at its best, keep the lid firmly closed and store it somewhere cool and away from direct sunlight, not on a warm, steamy bathroom bench.
Using Vitamin C After In-Clinic Treatments
After treatments like laser, Alma Harmony, microneedling or peels, your skin is in a recovery phase and needs gentle support. The right antioxidant serum can be a valuable part of your aftercare, but the timing and choice of serum matter.
“After a treatment, I’ll tell each client exactly when to reintroduce their vitamin C and which one to use. Some skin is ready for Pro-Heal almost straight away, while other active serums are best paused for a few days.”
Always follow the specific aftercare instructions you're given in clinic, as every treatment and every skin is different.
Common Vitamin C mistakes to avoid
Choosing by trend, not skin type. The serum your friend loves may not suit your skin.
Applying to damp skin. Most clinical vitamin C serums are designed to go onto dry skin.
Skipping sunscreen. Vitamin C supports your skin's defences, it doesn't replace SPF.
Storing it in the bathroom. Heat, light and humidity can affect your serum over time.
Layering too many actives at once. More isn't always better, especially for sensitive skin.
“The most common mistake I see is people using three or four strong actives at once and wondering why their skin is irritated. A well-chosen vitamin C, a good moisturiser and SPF will do more for you than overwhelming your skin with too many products.”
Still not sure which vitamin C serum is right for you?
If you're unsure where to start, I'd love to help. In a skin consultation, I'll assess your skin in person and recommend the vitamin C serum, and the routine around it, that's right for you.
Frequently asked questions
Should I use vitamin C serum in the morning or at night? Most vitamin C serums are best used in the morning, as they help support your skin's defences against environmental stressors during the day. Some formulas, like iS Clinical Pro-Heal Serum Advance+, can be used morning and night.
Do I apply vitamin C serum before or after sunscreen? Apply vitamin C serum before sunscreen. Cleanse, apply your vitamin C to dry skin, follow with moisturiser, then finish with sunscreen as your final step.
Can I use vitamin C and retinol together? Yes, but most people do best using them at different times of day. Use vitamin C in the morning and retinol at night, and introduce new actives gradually if your skin is sensitive.
Which vitamin C serum is best for sensitive skin? For sensitive skin, SkinCeuticals C E Ferulic, SkinCeuticals Phloretin CF Gel and iS Clinical Pro-Heal Serum Advance+ are often good starting points. Pro-Heal is especially suited to redness-prone or reactive skin. A skin consultation is the best way to find the right match.
Is vitamin C serum good for pigmentation? Vitamin C is known for supporting a brighter, more even-looking complexion. SkinCeuticals Phloretin CF Gel is designed with a focus on discolouration and uneven tone, and daily sunscreen is essential for anyone managing pigmentation.
How long does vitamin C serum take to show results? Vitamin C works gradually with consistent daily use. Give any new serum around 12 weeks before judging how it's working for your skin.
Why has my vitamin C serum changed colour? L-ascorbic acid naturally oxidises over time when exposed to air, light and heat, which can cause a serum to darken. Keep the lid closed and store it somewhere cool. If your serum has turned a deep brown, it's time to replace it.
Find your perfect Vitamin C match
Ready to give your skin the antioxidant support it deserves? Shop the iS Clinical and SkinCeuticals range at JBH Aesthetics and enjoy 15% off your first order, free shipping on all orders across Australia and complimentary samples in every order.
Buy any two full size SkinCeuticals serums and receive a complimentary 15ml Discoloration Defense Dark Spot Corrector, valued at $95.50, with code FREESKINCSERUM. Only while stocks last. T&Cs apply. (Delete offer when the gift with purchase ends)
By Jessica Bugeja Huon, Cosmetic and Dermatology Registered Nurse and founder of JBH Aesthetics, Camden NSW.
Last updated 9th October 2026.