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What’s a vitamin C serum?

If you have your head in the skin care game, you’ve likely heard of vitamin C serums.

Vitamin C is touted as one of the best anti-aging ingredients on the market — and the key to maintaining a smooth, even, and glowy complexion.

Although you’re probably getting vitamin C in your diet, there’s no way to guarantee it’s going straight to your skin. Using serums and other topical products is the most direct way to reap these benefits.

Read on to learn why you should add vitamin C serum to your routine, how to introduce a new product, and more.

Whether it’s a tried-and-true skin care regimen, how often you wash your hair, or the cosmetics you’re curious about, beauty is personal.

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There are plenty of benefits to using vitamin C on your skin. They include:

  • safe for most skin types
  • hydration
  • brightening
  • reduce redness
  • reduce hyperpigmentation
  • reduces the appearance of under-eye circles
  • promotes collagen production
  • may help prevent sagging
  • may protect against sun damage
  • may soothe sunburns
  • may help wound healing

1. It’s safe for most skin types

Vitamin C has an excellent safety profile. Most people can use topical vitamin C for an extended period of time without experiencing any adverse reactions.

In rare cases, people who have hypersensitive skin may experience minor irritation.

Vitamin C is also safe to use with other skin care actives, including alpha hydroxy acids, retinols, and SPF.

2. It’s hydrating

According to a 2017 research review, most healthy skin and organs contain high concentrations of vitamin C, suggesting that vitamin C accumulates in the body from circulation.

Review authors noted that topical vitamin C penetrates the skin best in the form of ascorbic acid.

Magnesium ascorbyl phosphate, another vitamin C derivative used in skin care, has been shown to have a hydrating effect on skin, according to a 2013 review. It decreases transepidermal water loss (TEWL), allowing your skin to better retain moisture.

According to a 2019 study, an antipollution, antioxidant serum containing Deschampsia antarctica extract, ferulic acid, and vitamin C reduced TEWL by 19 percent, improving the skin barrier function.

3. It’s brightening

Vitamin C can help fade pigmentation (more on this below!) and smooth the skin’s surface to reduce dullness. This gives skin a youthful glow.

A 2017 review notes that vitamin C application has been shown to impede melanin production, the pigment responsible for skin color. This can help fade dark spots and general dullness that prevent you from getting that dewy glow.

4. It helps reduce redness and even out your skin tone

Vitamin C has also been shown to act as an anti-inflammatory agent through its antioxidant capacity, according to a 2015 review. This means it soothes your skin and reduces puffiness, letting your face shine through.

Vitamin C’s anti-inflammatory action may help:

  • neutralize free radicals that cause oxidative damage
  • optimize the immune system to discourage inflammatory immune response

The anti-inflammatory properties of vitamin C can also help reduce redness, which in turn can create a more even complexion. The combined reduction of dark spots, redness, and irritation make for a clear, smooth skin tone.

5. It helps fade hyperpigmentation

Since it impedes melanin production, vitamin C can actually fade hyperpigmentation.

Hyperpigmentation — including sunspots, age spots, and melasma — occurs when melanin is overproduced in certain areas of the skin. It can also happen in areas where acne has healed.

Vitamin C inhibits melanin synthesis by downregulating the activity of an enzyme known as tyrosinase. It’s widely used in dermatology for depigmentation of hyperpigmented spots on the skin.

It’s also been used for treatment of gingival melanin hyperpigmentation (gum hyperpigmentation), though studies are limited.

Dealing with acne? Vitamin C isn’t your only option. Learn more.

6. It reduces the appearance of under-eye circles

Vitamin C serums can help smooth out fine lines by plumping and hydrating the under-eye area.

Although vitamin C is more effective at reducing overall redness, some people say it can help alleviate discoloration associated with under-eye circles.

According to a small 2009 study, vitamin C in the form of 10 percent sodium ascorbate was found to improve dark circles of the lower eyelid after 6 months of use by thickening the eyelid dermis and concealing dark coloration due to congested blood.

Some other ways to help get rid of under-eye bags include using a cold compress and adding retinol to your skin care routine.

7. It promotes collagen production

Collagen is a naturally occurring protein that depletes over time. Lower levels of collagen can lead to fine lines and wrinkles.

Vitamin C is well known for boosting collagen production through the process of collagen synthesis. In fact, collagen synthesis can’t happen without vitamin C.

This is because vitamin C is the essential cofactor for the two enzymes required for collagen synthesis:

  • prolyl hydroxylase, which stabilizes the collagen molecule
  • lysyl hydroxylase, which provides structural strength

Check out five other ways to boost collagen production.

8. It may help prevent skin sagging

Collagen production is tied to skin elasticity and firmness. When your collagen levels begin to drop, your skin may begin to sag.

Applying a vitamin C serum may boost collagen production, resulting in an overall tightening effect, reports a 2017 review. This is true for sagging due to natural aging, oxidative stress damage, or extreme weight loss.

This means it can help reduce the appearance of sagging skin, making your skin look firmer and more toned.

9. It protects against sun damage

Excessive exposure to oxidant stress via pollutants or UV irradiation is associated with depleted vitamin C levels in the skin. Vitamin C levels are also lower in aged or photodamaged skin, though researchers are unsure whether this is a cause or effect.

Sun damage is caused by molecules called free radicals. These are atoms with a missing electron. Free radicals search for other atoms from which they can “steal” an electron — and this can lead to significant damage to the skin.

Vitamin C is rich in antioxidants. Antioxidants protect healthy skin cells by “giving” these free radicals an electron, rendering them harmless.

10. It may help soothe sunburns

In addition to minimizing redness, vitamin C accelerates cell turnover, according to a 2013 review. This replaces the damaged cells with healthy new ones.

Topical application of vitamin C, in combination with vitamin E and other compounds, has also been shown to reduce injury due to UV irradiation (aka sunburn), notes the above 2013 review. This combination also decreases the inflammation induced by excessive UV exposure.

It’s important to note that researchers found that vitamin C alone is only minimally effective at reducing sunburn on its own.

11. It generally helps boost wound healing

Given its effects on sunburn, it should be no surprise that vitamin C application can speed up overall wound healing. Healthy wound healing reduces your risk of inflammation, infection, and scarring.

A 2017 review found that vitamin C supplementation had a positive effect on gene expression in human skin fibroblasts, including:

  • increased mitogenic stimulation, or cell proliferation
  • increased cell motility, or the spontaneous movement of a cell from one location to another by consumption of energy
  • faster repair of damaged DNA bases

This is in part because wound healing is associated with collagen formation, and vitamin C boosts collagen production.

Although topical vitamin C is generally well tolerated, all skin products have the potential to cause side effects. You should always do a patch test to assess your risk of allergic reaction. Here’s how:

  1. Select a small area of skin that’s easy to conceal, like your forearm.
  2. Apply a small amount of product and wait 24 hours.
  3. If no side effects occur, you can apply to your face. Discontinue use if you develop a rash, redness, or hives.

When it’s time for a full application, follow the instructions on the product’s label.

Vitamin C serum is typically applied once or twice per day. A good rule of thumb is to cleanse, tone, apply vitamin C serum, and then moisturize.

It can be safely used with other active ingredients, although using alongside niacinamide may make vitamin C less effective.

According to a 2020 review, a combination of tyrosine, zinc, and vitamin C was shown to increase the bioavailability of vitamin C 20 times than just vitamin C alone.

Make sure to check your product’s use-by date. If the product has darkened or otherwise changed color, the vitamin C has likely oxidized. Although the product is still safe to use, it no longer carries the same benefits.

Although irritation is unlikely, you should always do a patch test before full application. This is the only way to determine how your skin will react to the serum.

If your skin is especially sensitive, avoid products with L-ascorbic acid. Products with magnesium ascorbyl phosphate may be less likely to cause irritation.

Serum stability is affected by two things: product formulation and packaging.

The following vitamin C derivatives are designed to retain potency for longer:

  • L-ascorbic acid
  • ascorbyl palmitate
  • magnesium ascorbyl phosphate

You should also ensure that the product has a water-free formulation. And the bottle should be opaque and airtight.

Popular vitamin C serums include:

Vitamin C can help heal blemishes, reduce hyperpigmentation, and give your skin an out-of-this-world glow.

Consistency is key for maximum effect, so add it to your skin care routine in a way that makes sense for you. Some people apply it in the morning to take advantage of its UV-protectant properties, while others find that it works best as a night serum.

Discontinue use if you begin to experience irritation or discomfort.