Vitamin C: how to choose between a food supplement and a facial serum

Vitamin C comes in many forms: tablets, liquid solutions, liposomal formulas, facial treatments with ascorbic acid and serums containing stabilised derivatives. This variety caters to different needs, but it can also make choosing the right product more complicated.

Before you buy, keep these three common pitfalls in mind:

• Confusing percentage with actual effectiveness: a serum labelled 20 % is not necessarily more suitable than a less concentrated formula. The form used, the product’s stability and your skin’s tolerance are equally important.
• Choosing a high dosage without checking the usage recommendations: 1000 mg vitamin C may be suitable for some adults, but it is best not to take it alongside other supplements that already contain ascorbic acid without careful consideration.
• Assuming a supplement and a facial treatment serve the same purpose: a vitamin C food supplement is taken orally, while a serum works locally as part of your skincare routine. One does not replace the other.

What to check before buying

1. The form of vitamin C

Check the exact form used on the label.

• Ascorbic acid or L-ascorbic acid: this is the direct form, commonly found in supplements and certain serums. Although highly concentrated, it may be less comfortable for sensitive skin.
• Ascorbyl glucoside: this derivative is often used in brightening treatments and glow-boosting serums. It is generally considered a more gradual option.
• 3-O-ethyl ascorbic acid: this stabilised derivative is used in many facial treatments, particularly those designed to reduce the appearance of pigmentation.
• Liposomal vitamin C: the vitamin is combined with phospholipids in a liquid or capsule formula. Check the actual amount provided per daily serving, rather than relying solely on the term “liposomal”.

For a food supplement, also check the reference nutrient value (NRV). A 1000 mg dose corresponds to 1 250 % of the European NRV stated on several products featured here. This figure describes the product’s nutritional content; it is not personalised advice.

2. The dosage and daily serving

1000 mg vitamin C may be supplied per tablet, per serving of two capsules or per 10 ml serving of liquid. These formats are therefore not directly comparable.

Always check:

1. the amount per tablet, capsule or 10 ml measure;
2. the number of units recommended each day;
3. the intended duration of use;
4. whether sweeteners, polyols, sodium or added sugars are present.

Vitamin C effervescent tablets are convenient at work or while travelling. However, some formulas contain polyols, which can cause digestive discomfort if consumed excessively. If you follow a specific diet, also check the packaging for the vegan, gluten-free, lactose-free and no added sugar claims.

3. Stability and skin tolerance

For an anti-blemish or radiance serum, the INCI list provides more useful information than marketing claims alone. In particular, look for:

• the position of vitamin C or its derivative in the ingredients list;
• the presence of complementary active ingredients such as niacinamide, hyaluronic acid, vitamin E or glycolic acid;
• the presence of denatured alcohol, fragrance or exfoliating acids if your skin reacts easily;
• the type of bottle: opaque packaging or packaging designed to limit exposure to light may protect the formula more effectively.

A serum containing glycolic or salicylic acid should be introduced gradually. Carry out a patch test on a small area before applying it for the first time and use sun protection in the morning. If redness, itching, a burning sensation or swelling occurs, stop using the product immediately.

Our selection for your needs

Recommended for : Beginners on a budget

The Ordinary Ascorbyl Glucoside Solution 12% 30ml

Why this choice suits this profile : Its water-based texture, free from fragrance and silicone, fits easily into a simple routine for discovering a vitamin C serum without layering multiple active ingredients.

How this product avoids the pitfall

The product details state that it contains 12 % ascorbyl glucoside and has a fragrance-free formula, rather than relying solely on a striking percentage.

Main benefit and key features

Water-soluble derivative, 30 ml format, with morning and evening application according to the product instructions.

Recommended for : Premium skincare enthusiasts

Quality 1st Ulthera C Essence 30ml

Why this choice suits this profile : This Japanese essence is designed for those who want to combine several forms of vitamin C with complementary ingredients in a single treatment.

How this product avoids the pitfall

The product details list four forms of vitamin C and state a concentration of 25 % niacinamide, making the formula easier to understand.

Main benefit and key features

30 ml format, with ceramides and hydrolysed hyaluronic acid, in a formula stated to be free from ethanol alcohol and preservatives.

Recommended for : Specific uses and intensive users

WeightWorld Liposomal Vitamin C 1000mg 180 Capsules

Why this choice suits this profile : The tasteless capsule format suits people looking for a regular intake and a vegan, gluten-free formula.

How this product avoids the pitfall

The stated 1000 mg dose corresponds to two capsules, not one. This clarification prevents any misunderstanding of the dosage.

Main benefit and key features

180 capsules, sunflower phospholipids, rosehip extract and a recommendation to store away from light.

Recommended for : Targeted anti-blemish routine

MIXA Lab Vitamin C and Glycolic Acid Anti-Pigmentation Concentrated Serum, 30 ml

Why this choice suits this profile : The formula combines vitamin Cg, glycolic acid, niacinamide and salicylic acid to target an uneven-looking complexion.

How this product avoids the pitfall

The presence of several exfoliating active ingredients is clearly stated : you can therefore start gradually instead of layering several acids.

Main benefit and key features

Made in France, 30 ml, with glycerine and sodium hyaluronate to boost the hydrating effect.

Frequently asked questions about vitamin C

Which form should you choose to support immunity ?

A food supplement containing ascorbic acid, a formula enriched with bioflavonoids or liposomal vitamin C may be considered depending on your preferences and the nutritional information provided. Follow the recommended dose, avoid duplicate ingredients and seek advice from a healthcare professional if you are pregnant, breastfeeding, taking medication or have a history of kidney stones.

How long can you keep a vitamin C serum ?

Follow the use-by date and period after opening stated on the packaging. Close the bottle promptly and store it in a cool, dry place away from light. If the colour, smell or texture changes noticeably, it is best to stop using it.

Can you apply a vitamin C serum every day ?

The frequency depends on the form used, its concentration and your skin’s tolerance. If your serum contains ascorbic, glycolic or salicylic acid, start with a few applications per week. Then apply a moisturiser and, in the morning, sun protection. Vitamin C does not replace sun protection.