Vitamin C: The Complete Guide To Vitamin C Everything You Need To Know About This Miraculous Little Ingredient



You already know that consuming vitamin C is good for your health, and you may load up on oranges and grapefruits to give yourself an extra boost during the winter cold season.

Vitamin C occurs naturally in the skin, but also has plenty of benefits when applied topically. Here’s a closer look at what vitamin C is, where to find it, and what it can do for your skin.

Related: Best Vitamin C Serums

What is Vitamin C?

According to the National Institute of Health, vitamin C, also known as ascorbic acid, is a water soluble nutrient. Bodies need it to form muscle and collagen, which assists in wound healing and keeping skin looking plump and a firm. 

Vitamin C is also considered to be an antioxidant in the body and according to the Mayo Clinic, may help protect against damaging free radicals. Vitamin C is found in citrus fruit as well as broccoli, peppers, baked potatoes, and tomatoes.  

Vitamin C is found naturally in the skin. In a 2017 article, the authors note that ‘normal skin contains high concentrations of vitamin C, which supports important and well-known functions, stimulating collagen synthesis and assisting in antioxidant protection against UV-induced photodamage.’

L-ascorbic acid

the good: Helps to maintain skin barrier integrity, fights pigmentation, may be involved in inflammation processes in the skin, is involved in collagen production, and protects against sun damage.

the not so good: Highly unstable molecule that makes formulating difficult. This is why it is important to know what to look for when purchasing a vitamin C product.

Who is it for? All skin types. People with sensitive skin types should use a lower concentration of vitamin C and reduce the frequency of use.

Synergetic ingredients: Vitamin E and ferulic acid.

Keep an eye on: The source of vitamin C, the concentration and type of vitamin C product. Product types include gels, serums and powders.

What are the Best Skin Care Products of 2024?

What Is Topical Vitamin C?

The vitamin C found in skincare products is usually listed as ascorbic acid, L-ascorbic acid, magnesium ascorbyl phosphate, sodium ascorbyl phosphatem ascorbyl palmitate and retinyl ascorbate.  The most commonly used is L-ascorbic acid, and it is also the most researched.

According to the University of Wisconsin-Madison, L-ascorbic acid is the purest and most potent form of vitamin C, and the only version of it that can fully be absorbed by the skin. ‘Once L-ascorbic acid is applied to the skin it is immediately absorbed, cannot be washed off, and will remain in the skin for up to 72 hours.’

What Are The Benefits of Vitamin C?

L-ascorbic acid is a powerhouse ingredient that can help improve the appearance of the skin in multiple ways, making it an ideal product to bring into any skincare regime. Studies discussed in the Journal of Clinical and Aesthetic Dermatology have outlined the benefits of topical vitamin C treatments. 

Their research found evidence that topical vitamin C may help diminish the visibility of pigmentation, is involved in the collagen production process, may be involved in inflammation, reduce the sun’s effects on the skin, and maintain skin barrier integrity.



Vitamin C is best known for helping to make the skin look brighter.  Since vitamin C is an acid, it helps whisk away dead skin cells, which leaves the face looking smoother and brighter, and feeling softer. It may also inhibit melanin production, which results in skin looking brighter. Regular use may also help to minimize the appearance of fine lines due to cell turnover.



Environmental factors such as radiation from the sun, UVA and UVB, pollution, smoking, and diet can put the skin in a state of oxidative stress. Oxidative stress produces an imbalance in the levels of molecules called free radicals. This imbalance may lead to damage of cells and tissues within the body. 

Free radicals, also called reactive oxygen species or ROS, are a natural by-product of the body’s chemical processes. Think of them as your body’s waste. Free radicals can accumulate and create an imbalance. 

This imbalance has been studied for its links with many diseases and its role in the aging process. As an antioxidant, vitamin C is thought to reduce the effects of oxidative stress by neutralizing the free radical molecules and rebalancing their levels in the body. 


Vitamin C and sun damage

When skin is exposed to UV light, it can produce free radicals. Free radicals are involved in a cascade of events that have been suggested to reduce the amount of collagen the body produces, increase cellular damage, and may cause harm to the DNA within the cell. 

The effects of free radicals on the skin result in the appearance of deep wrinkles, pigmentation, and loss of elasticity. These changes also tend to be associated with the natural decrease in collagen production and sun damage as we age

As an antioxidant, vitamin C neutralizes the free radicals formed by exposure to the sun, giving vitamin C protective and restorative qualities against sun damage.

 Sunscreen remains the most effective way of reducing the effects of sun exposure. Still, studies have shown that vitamin C can enhance the protective abilities of sunscreens and help fight some of the visible pigmentation associated with sun damage.

Evidence from several studies displayed the protective properties of vitamin C against the sun’s harmful effects.  These studies suggest that vitamin C and another antioxidant, vitamin E, heighten the protective abilities against the sun in sunscreen formulations. Dermatologists might recommend using a vitamin C serum containing vitamin E before sunscreen to harness vitamin C’s ability to neutralize or rebalance the free radicals in the skin.

Vitamin C also helps to replenish vitamin E levels in the skin. Vitamin E, an antioxidant like vitamin C, has been studied for its involvement in immune function, maintaining skin health, and its abilities in supporting the skin to protect itself from UV damage. 

A 1999 article in the Aesthetic Surgery Journal discussed that new studies show that topical vitamin C is an excellent antioxidant for UVA and UVB protection, making it a useful adjunct to, but not replacement for, sunscreens. 

This research was followed up in 2011 by researchers at the Linus Pauling Institute. Their research suggested that despite inconsistencies in vitamin C formulations, vitamin C is effective at protecting against damage induced by UV light. They also noted that it may help support the treatment of photodamage and/or skin wrinkling. 



As we age, collagen production decreases. From age 20, the amount of collagen produced reduces by 1% per year. As a molecule, L-ascorbic acid has been studied for its role in pathways that produce collagen in the body. 

Collagen forms crosslinked fibers in the deeper layers of the skin which creates a net-like structure. It is thought that collagen may provide the skin with structure,  firmness, or elasticity.

Vitamin C acts as a cofactor or a helper molecule in the body’s natural collagen forming process. Studies have looked at L-ascorbic acid’s ability to crosslink and stabilize collagen fibers. Vitamin C has also been investigated for its involvement in the production of a molecule called procollagen mRNA. This molecule signals the production of collagen and is responsible for signaling to the cell that collagen is needed.

While several studies support vitamin C’s involvement in the processes that produce collagen, research is ongoing as to whether skincare products containing vitamin C have significant effects in improving visible firmness and elasticity of the skin.  

As the skin is the last organ to receive dietary vitamin C, topical L-ascorbic acid products such as powders and serums may be beneficial to improve the appearance of the skin. A study of vitamin C in skincare identified that topical L-ascorbic acid products increased L-ascorbic acid levels in the skin. The study also found that vitamin C products could improve the appearance of the skin at any age.  

In 2015 in the Clinical, Cosmetic and Investigational Dermatology Journal published an article, which found that applying a 5% vitamin C solution for 6 months increased the skin’s thickness. Thicker skin is less likely to wrinkle than thin skin. 


Hyperpigmentation and L-ascorbic acid

Hyperpigmentation occurs on the surface of the skin for a multitude of internal and external reasons. These can range from pregnancy or melasma, hormonal imbalance, and sun damage to genetic predispositions, injury, or inflammation.

Melanin is the molecule responsible for giving skin color or pigment, and the uneven production of melanin results in hyperpigmentation areas on the surface. Vitamin C works to reduce the visibility of pigmentation through inhibition of the enzyme responsible for producing melanin in the skin. 

By inhibiting the irregular production of melanin, vitamin C, at the right concentration and pH, can help minimize pigmentation’s appearance.  

Dermatologists might recommend concentrated vitamin C products alongside retinol and laser for pigmentation. Using vitamin C to reduce the appearance of pigmentation can take time and depend on the product’s strength and frequency of use.

It is crucial to use sunscreen alongside vitamin C products to avoid further pigmentation from the sun.  



Inflammation in the skin is common but some people experience it on a daily basis. Conditions such as acne, psoriasis, rosacea, and eczema may cause the skin to be chronically inflamed. 

Vitamin C is thought to inhibit a molecule that activates pro-inflammatory cytokines. Cytokines are involved in immunity and help produce the inflammation reaction in the body to heal – think of healthy wound healing. In conditions where the skin is chronically inflamed, the cytokines react inappropriately, often working in overdrive. Currently, topical vitamin C products are being examined for how it is involved in inflammation, wound healing and post-inflammatory linked pigmentation. 


Skin barrier integrity

The skin barrier includes the outermost layers of the skin and is essential for maintaining a healthy, clear complexion. It is responsible for protecting the skin’s deeper layers from damage, allergens, bacteria, and moisture loss. When issues with the skin barrier occur, it may suggest conditions such as atopic dermatitis or eczema. 

Vitamin C has been used in combination with other skincare ingredients and dermatological therapies to treat conditions that affect the skin barrier. Vitamin C is thought to maintain the skin barrier by enhancing the ability of keratinocytes. Keratinocytes are a type of skin cell that produces keratin. Vitamin C helps to specialize the function of the keratinocyte. 

Which Skincare Products Contain Vitamin C?

Vitamin C is found in several skincare products such as serums, moisturizers, masks, toners, face mists, oils, masks, eye creams and cleansers. Some companies sell vitamin C-based spot treatments to target discoloration, as well as dissolvable sheets.  It is also sold in a powder form that can be added to a moisturizer or serum or mixed with water.

 The most common way to get vitamin C is in a serum, as they are lightweight, absorbed quickly and can be layered under products. Only a few drops of a serum are needed and most people apply it under a moisturizer in the morning. In general vitamin C is found in water-based products or in an anhydrous one- which means without water, such as a powder form.  

 All vitamin C based products should be stored in a cool, dry place away from direct sunlight.

How Should Vitamin C Be Used?

The vitamin C product you select should dictate how and when it should be used. If you’re using a vitamin C serum, it should be applied in the morning as it may help protect the skin against UV rays. Some vitamin C infused products are meant to be used specifically at night, so always read the label carefully.

Who Should Use Vitamin C?

Vitamin C is suitable for all skin types and ages, whether you are young or mature, and have dry, oily, normal or sensitive skin. 

However as with all products, irritation can occur so as a rule of thumb it’s best to test patch first and see how your skin reacts.

What Percentage of Vitamin C Should I Look For?

Every product contains varying amounts of vitamin C. Read the label carefully. Most products tend to contain between 15-20% vitamin C, while some go up to 30%.

Generally studies have shown that vitamin C products that range between 8-20% are best. While it may be tempting to go for a higher concentration serum, doing so can actually irritate and potentially damage the skin. 

If you are new to vitamin C, start with a lower concentration a few nights a week and work your way up.

Can I DIY a Vitamin C Product?

While you may be a fan of an occasional yogurt-honey mask or applying slices of chilled cucumber to the eyes, DIY vitamin C is a little more in-depth. 

However, it is something you can do at home. Here our article on how to make your own vitamin C serum at home. 

Are There Any Downsides to Using Vitamin C?

Vitamin C isn’t very stable, which means it breaks down when exposed to light, heat and air, which can all render it less effective. Look for formulas in an air-tight package, a pump or a dark glass bottle. The addition of ferulic acid and vitamin E may help stabilize the formula. 

Vitamin C may also cause mild stinging or redness when first applied. It usually goes away with continued use but any concerns should be discussed with a healthcare provider. Magnesium ascorbyl phosphate, a water-soluble vitamin C, tends to be less irritating than L-asorbic acid so may be better for sensitive skin.

 If you’re using a product containing retinol, you may want to alternate days when retinol and vitamin C are used to avoid irritating the skin. If you are also using products with salicylic acid and glycolic acid, you may want to avoid using vitamin C-spiked products on the same day.

There is also a phenomenon where vitamin C can, when applied topically smell like self tanner. It can also leave a very mild tint to the skin. This doesn’t happen with every vitamin C product but can for some skin types. 

What Should You Consider When Choosing A Vitamin C Product?

 Many serums blend vitamin C with other antioxidants and vitamins. The right formula for you will depend on your skin type and concern, such as dry skin or anti-aging. 

If hydrating skin is a priority, look for a serum that also contains hyaluronic acid, a moisture magnet that can hold up to 1,000 times its weight in water, or glycerin, a humectant. Other serums contain additional fruit enzymes sourced from cloudberry, pomegranate or kakadu plums, to help exfoliate dead skin cells, which helps to leave skin looking and feeling softer. Some vitamin C serums contain ‘greens’ such as algae, spinach and kale for extra antioxidants.


Stability of your vitamin C product

L-ascorbic acid is a highly unstable molecule. It requires a water-based environment, a low pH, and antioxidants to increase its ability to deeply penetrate the skin. 

Those conditions are important for creating a stable and active vitamin C product. It is essential to understand why L-ascorbic acid requires these conditions when choosing a vitamin C product in order to find one that is effective and long-lasting. 

L-ascorbic acid has a reduced ability to penetrate the skin at its natural pH which is a result of its molecule structure. L-ascorbic acid is a charged molecule and is hydrophilic. These two characteristics mean that L-ascorbic acid will readily bind to water molecules, making it hard for the molecule to pass through the skin’s hydrophobic layers. 

Reducing the pH of a product to less than 3.5 or less makes it more acidic, allowing for L-ascorbic acid to penetrate deeper and be stable for longer.  However, reducing the pH of the product may lead to sensitization of the skin, as the natural pH of the skin is around. It is important to know the concentration of the product (more on that below). 

To create a more stable product that lasts longer, some formulations use different forms of vitamin C. This includes magnesium ascorbyl phosphate or ascorbyl-6-palmitate, which are more stable at a neutral pH. However, a study conducted by Duke University Medical Center found that these two substitutes did not increase the natural vitamin C levels in the skin.

Some formulations include other antioxidants to help stabilize the L-ascorbic acid. Studies have suggested that incorporating ferulic acid and vitamin E can increase stability and improve the product’s ability to penetrate deeply into the skin. 

A study published in the Journal for Investigative Dermatology found that ferulic acid stabilized the formulation and increased the protective capabilities of vitamin C to the sun’s effects.

L-ascorbic acid will only stay active in skincare products for a short period once opened. Even well-designed products will experience this, as exposure to the air will oxidize the L-ascorbic acid.  To increase a product’s longevity, look for powder formulations, products in vial form, or small product sizes. Look for products formulated with antioxidants such as ferulic acid. 



Concentration is another critical element when considering which L-ascorbic acid products would best suit your needs. Some brands advertise a high level of vitamin C in their product, such as 100% L-ascorbic acid. 

While it may seem appealing to have concentrated products, formulas with more than 20% L-ascorbic acid can irritate the skin. Most dermatological studies have found that a range between 8-20% produces the best results with limited irritation. 

A study conducted by Duke University Medical Center found that the concentrations of L-ascorbic acid above 20% do not have increased skin benefits. The study determined that conversely, higher levels can negatively impact the skin’s condition. Sensitive skin types should use vitamin C products in the lower part of the range.


Synthetic or plant-based vitamin C

Occasionally brands won’t advertise the strength of the vitamin C content in the product but instead focus on the source. This lack of information regarding concentration tends to occur with formulations utilizing Kakadu plum, hibiscus, or other plant-based vitamin C sources. 

The issue with plant-based sources of vitamin C is that they tend to be low in concentration and are generally unstable. The strength of L-ascorbic acid in Kakadu plum is about 2% which means it cannot affect the skin in any significant way. 

The low concentration of L-ascorbic acid in plant-based sources and the instability of most natural sources is why most effective vitamin C products use a synthetic form of L-ascorbic acid in their formulations, including most clean beauty brands. 


Vitamin C products

Many product types can deliver vitamin C to the skin, including gels, serums and powders. L-ascorbic acid is a water-soluble molecule that requires a low pH and the inclusion of stabilizers and antioxidants, which means that most L-ascorbic acid formulations will be in a water base or dried form. Some are formulated in an oil base.

L-ascorbic acid delivered in gel or serums is absorbed quickly without adding extra moisturizing products which makes them suitable for oily or acne-prone skin. They also work well with an established skincare routine, as they avoid disrupting a working regime. Powder forms of L-ascorbic acid prevent the need for many stabilizers. They reduce the risk of decreased effectiveness through exposure to the sun and air as the product becomes active only when mixed with water.


Other types of vitamin C

The type of vitamin C often varies between formulations. As a vitamin C source, L-ascorbic acid is the most well-researched source and the source that has shown the most benefits to the body. Other forms of synthetic vitamin C used in skincare are mineral ascorbates, calcium ascorbate, magnesium ascorbate, ascorbyl palmitate or tetrahexyldecyl ascorbate.  The type of vitamin C and the type of product can have a significant effect on the efficacy of the product.

Studies have indicated that tetrahexyldecyl ascorbate might equal L-ascorbic acid in terms of effectiveness. Tetrahexyldecyl ascorbate is an oil-soluble form of vitamin C that works alongside other products such as retinol. In a review conducted by the Cosmetic Ingredient Review, evidence indicated that tetrahexyldecyl ascorbate is more stable in solution, less irritating, and able to penetrate deeper into the skin, making it a promising vitamin C treatment. 

Can You Use Vitamin C with Retinol? 

Yes, you can but only if your skin and patience can handle it. If you want to use vitamin C and retinol together, start off slow. It’s best to apply vitamin C before your retinol product as vitamin C has a lower pH than retinol.

Let the vitamin C sink in first for 30 mins so that the vitamin C doesn’t interact with the pH of the retinol. 

The other way to combine these two ingredients is to alternate their use, use vitamin C one night and retinol the other.

Is Vitamin C Vegan?

Yes, vitamin C is usally a vegan ingredient. For the most part, all commonly used forms of vitamin C are synthetically made, with the exception of plant-based sources such as Kakadu plum and hibiscus. Here is a breakdown of the most commonly used vitamin C ingredients. 


Is L-ascorbic acid vegan?

L-ascorbic acid is a vegan ingredient as it is commercially produced from glucose, a sugar often derived from corn.


Is magnesium ascorbyl phosphate vegan?

Magnesium ascorbyl phosphate is a vegan ingredient. It is derived from ascorbic acid and a magnesium salt which are mixed with a phosphorylating ingredient. All of these ingredients are vegan. 


Is ascorbyl palmitate vegan?

Ascorbyl palmitate is a vegan ingredient. It is derived from ascorbic acid and palmitatic acid. For the most part palmitic acid is derived from plant-based sources as it is the most inexpensive form of manufacturing. 

However, it can also be made from animal-based products. For this reason it is always best to check with the brand that you intend on purchasing if their source is vegan.


Is tetrahexyldecyl ascorbate vegan?

Tetrehexyldecyl ascorbate is a vegan ingredient. It is made from sorbitol using various bioenzymatic and chemical processes. Sorbitol is derived from glucose, a natural sugar which is obtained from vegetable starch.

Is Vitamin C Safe During Preganancy? 

Vitamin C- based products are considered to be safe during pregnancy. However, it is always best to check with your doctor before starting any new active product. 

Can You Use Lemon Juice As A Vitamin C Treatment?

We wouldn’t recommend it, while lemon juice does contain vitamin C it is harsh on the skin and can lead to disruption of the skin’s natural barrier. Check out this article on why you shouldn’t use lemon juice on your skin. 


Al-Niami, F & Chiang, N 2017. ‘Topical Vitamin C and the Skin: Mechanisms of Action and Clinical Applications’, The Journal of Clinical and Aesthetic Dermatology, vol. 10, is. 7, pp. 14-17.
Chen, L, Hu, J, Wang, S 2012. ‘The role of antioxidants in photoprotection: A critical review’, Journal of the American Academy of Dermatology, vol 67, is. 5, pp.1013-1024. 
Murray, J, Burch, J, Streilein, R, Iannacchione, M, Hall, R & Pinnell, S 2008. ‘A topical antioxidant solution containing vitamins C and E stabilized by ferulic acid, provided protection for human skin against damage caused by ultraviolet radiation’ Journal of the American Academy of Dermatology, vol. 59, is. 3, pp. 418-425. 
Pinnell, S, Yang, H, Omar, M, Monteiro-Riviere, N, DeBuys, H, Walker, L, Wang, Y & Levine, M 2001. ‘Topical L-ascorbic Acid: Percutaneous Absorption Studies’, Dermatol Surg, vol.27, is. 2, pp.137-142. 
Pullar, J, Carr, A & Vissers, M 2017. ‘The Roles of Vitamin C in Skin Health’ Nutrients, vol. 9, is. 8, pp. 866. 
Telang, P 2013. ‘Vitamin C in dermatology’ Indian Dermatology Online Journal, Vol. 4, is. 2, pp. 143-146. 
Yatskayer, M, Oresajo, C, Bhushan, P, Yano, S & Stephens, T 2011. ‘Clinical evaluation of an antioxidant gel cream containing vitamin c, ferulic acid and phloretin on photodamaged skin’, Journal of the American Academy of Dermatology, vol. 64, is. 2, pp. 24.
Wang, K, Jiang, H, Li, W, Qiang, M, Dong, T & Li, H 2018. ‘Role of Vitamin C in Skin Diseases’, Frontiers in Physiology, vol. 9, pp. 819. 



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