Vitamin C Ampoule
How It Differs from a Serum and How to Choose

Vitamin C ampoule vs serum: the name does not tell you

"Ampoule" sounds richer and more concentrated than "serum." In practice, there is no set rule that separates the two.

Of the 2,426 full ingredient lists we have collected, 9 vitamin C products carry "ampoule" in the name, and some of them are filed as serums. So before ampoule versus serum, look at which form of vitamin C is inside and how much. For more on the ingredient itself, see the vitamin C ingredient guide and Vitamin C: 4 Forms Compared.

What vitamin C does for your skin

Most people reach for a vitamin C ampoule because of dark spots and a dull tone. Vitamin C is known for three things (Telang, 2013).

• Dark spots and tone: Melanin, the pigment behind spots, is made by an enzyme called tyrosinase. Vitamin C is known to get in that enzyme's way, so less melanin forms. That is why it is the go-to ingredient for spots.
• Firmness: Your skin needs vitamin C to build collagen, the protein that holds it up. The step that links collagen strands together depends on it.
• Sun stress: Sunlight creates free radicals in the skin. Vitamin C is an antioxidant that absorbs them first, which helps limit the damage.

The catch is that vitamin C has to reach inside the skin to do any of this. It breaks down easily in water, light and air. That is why brands put it in different forms, and the form is the most important thing to check when you buy.

Which skin suits a vitamin C ampoule

If dark spots or a dull tone bother you, vitamin C is the first ingredient to consider. If your skin has started to feel rougher and less firm, adding it to your evening routine is worth a try too.

The right form depends on your skin. If it is thin and flushes easily, pick a gentler derivative. If you have used the pure form before and your skin is sturdy, a product rich in pure vitamin C is fine. Either way, if it stings or reddens, take a break first.

Dry skin needs more than an ampoule, so always follow with cream. The good news is that vitamin C products often bring their own moisturizers. More than half of our 176 vitamin C derivative products also contain hyaluronic acid.

Pure vitamin C vs derivatives: what is the difference

The label may just say vitamin C, but the ingredient list uses other names. The pure form appears as ascorbic acid. Derivatives, which attach another molecule so vitamin C does not break down as fast, carry "ascorbyl" in the name, such as ascorbyl glucoside or sodium ascorbyl phosphate.

The pure form is the most studied, and also the fussiest. In one experiment it had to be formulated below pH 3.5 to get into the skin, and pushing the concentration past 20% added nothing (Pinnell et al., 2001). The low pH and its instability are why many people feel a sting.

Derivatives are gentler and last longer, but they only work once the skin turns them back into vitamin C. How much converts depends on the type, and in the same study some derivatives did not raise vitamin C levels in the skin. If spots are your goal, a handy shortcut is the Korean MFDS list of whitening functional ingredients: ascorbyl glucoside, ethyl ascorbyl ether, magnesium ascorbyl phosphate and ascorbyl tetraisopalmitate.

How to choose a vitamin C ampoule

• Form: For sensitive skin, choose a derivative with "ascorbyl" in the name. For sturdy skin that wants more effect, choose ascorbic acid (the pure form).
• How much is in it: Ingredient lists start with what there is most of. If vitamin C sits near the end, there is only a little. Putting vitamin C in the product name did not mean more of it in our products, so check the list once.
• Container and size: The ingredient is sensitive to light and air, so a dark bottle or an airless pump is best. A small size you can finish in a month or two is better still.

Ampoule and serum products with plenty of vitamin C

From our collection, we picked only products that put in a generous amount of vitamin C. Ampoules first.

• Laneige Radian-C Vitamin Spot Ampoule has the most pure vitamin C of the ampoules we looked at, plus a derivative. If the pure form is new to you, start every other day.
• Mamicare Orthotamine Vitamin C Ampoule is generous with both the pure form and a derivative. Its ingredient list is long, so it may not suit you if you prefer simple formulas.
• Missha Vita C Plus Spot Correcting Firming Ampoule is derivative-based. The Intensive Ampoule in the same line leans on the pure form, so pick the one that fits your skin.
• Torriden Cellmazing Vita C Brightening Ampoule is a gentle option with plenty of the derivative ethyl ascorbyl ether. Sensitive skin that finds the pure form too much should look here first.

Among serums and essences, The Ordinary's Ascorbyl Glucoside Solution 12%, Primera Vitatinol Bouncy Lift Serum and Kiehl's Powerful Vitamin C Essence also carry a generous amount of a derivative. For a product not listed here, enter its name to analyze the ingredients.

How to apply a vitamin C ampoule and what to watch

• Order: Cleanse, tone, apply the ampoule and finish with cream. If the product's directions say otherwise, follow them.
• Start slowly: Begin once a day, or every other day for a product rich in the pure form.
• In the daytime: Always wear sunscreen too. Vitamin C does not block UV on its own.
• Storage: Close the cap right away and keep it out of sunlight. If the color darkens noticeably, it is time for a new bottle.

Frequently asked questions

Can I use a vitamin C ampoule every day?

An ampoule rich in pure vitamin C (ascorbic acid) can sting or redden skin, so start every other day. Derivative-based ampoules tend to be gentler, but watch how your skin responds before using it more often.

Is an ampoule better than a serum?

The name alone does not settle it. There is no set rule separating the two, so you will find gentle ampoules and strong serums. Look at which form of vitamin C is inside and how much.

My vitamin C ampoule turned brown. Can I still use it?

Vitamin C oxidizes in light and air, and the color changes as it does. If it is noticeably darker than when you opened it, the ingredient has changed, so a new bottle is the safer choice.

Can I use a vitamin C ampoule in the morning?

Yes. As an antioxidant that absorbs free radicals, it has a reason to be on your skin during the day. It does not block UV on its own, though, so wear sunscreen too.