All About Topical Vitamin C: One of the Best Ways to Protect Your Skin.

02 April 2020

You’re in for a treat today! In this post, I’ll be sharing about one of the best ways to protect and age proof your skin using skincare with vitamin C (of course, do not neglect your sunscreen and retinoids)!

Highly favoured and recommended by doctors, vitamin C is an easy and effective way to also brighten your skin, lighten pigmentation and age-proof skin. However, information regarding topical vitamin C is often confusing and sometimes, inaccurate. Adding to this confusion is the vast array of choices of vitamin C skincare available; making it overwhelming for consumers when it comes to selecting a vitamin C product for their skin. So here this is, a guide to the science, benefits and recommendations for vitamin C in skincare. I hope you find this roadmap useful!


1. Vitamin C as a potent antioxidant that protects the skin against harmful environmental stressors

• UV rays and the environmental factors such pollution and smoking form free radicals which cause oxidative stress to the skin and this accelerates damage and aging to the skin. • Vitamin C neutralises free radicals by donating electrons to these free radicals, preventing damage to the skin.

2. Vitamin C protects against skin cancer

• UV rays from the sun can cause skin cancer by inducing DNA damage to the cells of the skin and a very important gene called the p53 gene. The p53 gene is the known as the gatekeeper of gene because the p53 gene is responsible for the repair of damaged DNA which cause cells to mutate (and become cancerous); and the removal of these damaged DNA to prevent cancer.

3. Vitamin C protects the skin against UV rays of the sun including sunburns

• Laboratory studies have shown that topical application of 10% vitamin C reduces UV induced sunburn by 40-60% and UV induced redness by 52%. • Sunscreens only block out 55% of the free radicals • To optimise UV protection, combine the use of a sunscreen with a topical vitamin C to neutralise free radicals that are not blocked out by sunscreens.

4. Vitamin C for anti-aging effects and collagen synthesis

• Collagen synthesis requires vitamin C • Vitamin C also increases collagen levels in the skin by decreasing degradation of collagen.

5. Vitamin C lightens pigmentation

• Vitamin C plays an important role in reducing pigmentation by inhibiting the enzyme tyrosinase which is needed to form melanin.

6. Vitamin C replenishes vitamin E, another antioxidant in the skin that protects skin cells and maintains collagen levels in the skin.

• Aside from its anti-aging and pigmentation lightening benefits, vitamin C also replenishes vitamin E. Vitamin E is another antioxidant that protects cells against free radicals and maintains collagen levels in the skin.


Unfortunately, humans lack the ability to synthesise vitamin C and therefore we have to rely on external sources of vitamin C- either as topical vitamin C in skincare or as part of a Skinbooster cocktail that is injected into the skin1,2. More about vitamin C in Skinboosters in this review, Skinboosters: All You Need to Know About It.

Let us first discuss the topical vitamin C in skincare to reap the benefits of vitamin C on our skin. The great thing about this is that you can get vitamin C in various formulations in skincare over the counter at affordable prices.

My recommendation would be to use vitamin C at least once daily (preferably, L-ascorbic acid- and you will understand why as you read on below). Vitamin C/L-ascorbic acid is commonly found in serums or moisturiser as a long as the concentration is adequate. This is where things start to become confusing- how do you choose a vitamin C serum for your skin?


Let us first understand the basics of vitamin C so that we can understand how to choose the type of vitamin C.

There is a wide array of vitamin C serums available and a look at in the ingredient list of drugstore vitamin C serums will unveil these familiar suspects:

1. L-ascorbic acid 2. Vitamin C derivatives/ L-ascorbic acid derivatives/esters • Magnesium ascorbyl phosphate • Sodium ascorbyl phosphate • Ascorbyl glucoside • Ascorbyl tetraisopalmitate • (and many more)

Vitamin C is also known as ascorbic acid and ascorbic acid exists in 2 forms which are mirror images of each other (isomers), L-ascorbic acid and D-ascorbic acid. The only chemically active form of ascorbic acid is L-ascorbic acid; this is the form that acts on the skin to bring about all the dermatological benefits mentioned above1. D-ascorbic acid on the other hand, does nothing to the skin. L-ascorbic acid is in fact the bona fide vitamin C that works on our skin and you can consider L-ascorbic acid as ‘1st generation’ vitamin C.


Related post: How to Lighten Pigmentation and Dark Spots with Skincare.


True, active vitamin C (L-ascorbic acid) is unstable, with sunlight exposure reducing its efficacy and shelf life. Skincare companies have been trying to improve the shelf life of L-ascorbic acid by introducing vitamin C derivatives or the more stylishly named ‘2nd generation vitamin C’- which promise the same results of L-ascorbic but with greater stability and longer shelf lives. Despite the popularity of ascorbic acid derivatives, the efficacy of these derivatives is still questionable.

Thankfully, there are ways to overcome this finnicky nature of L-ascorbic acid without compromising the effectiveness of vitamin C. One way is to reduce the pH to below 3.54. This improves both the stability of L-ascorbic acid and permeability to reach the deeper layers of the skin. A second way method would be the addition of ferulic acids (another antioxidant) to achieve both stabilisation of L-ascorbic and a pH below 3.55,6. Examples of L-ascobic acid serums that contain ferulic and a pH 3.5 are Skinceuticals’ C E Ferulic; Drunk Elephant’s C Firma and La Clinic’s Vitamin C serum formulated by myself. No surprises here that these happen to be my favourites. Afterall, why not make things better if you can formulate your own skincare?

The problem with vitamin C derivatives or 2nd generation vitamin C is that not all of these preparations are physiologically effective7,8. These ascorbic acid derivatives are pro-drugs that need to be enzymatically converted back to L-ascorbic acid to act on the skin9. These ascorbic acid derivatives or ‘2nd generation vitamin C’ are of no use to the skin by themselves. Some are not delivered into the dermis in an adequate quantity while others do not chemically convert to the biologically active form of vitamin C (L-ascorbic acid) in the skin. Exactly how much of these ascorbic acid derivatives get converted to L-ascorbic acid is unclear9. In other words, magnesium ascorbyl phosphate concentration 0f 20% is not equivalent to an L-ascorbic acid concentration of 20%.

Some of the more common vitamin C derivatives such as magnesium ascorbyl phosphate (MAP) and ascorbyl phosphate claim to have better penetration and uptake by the skin but one study showed that daily application of MAP, ascorbyl palmitate and other ascorbic acid derivatives did not increase the levels of L-ascorbic acid in the skin4. My recommendation? Stick to what is true, tried and tested because we are more certain about the efficacy with L-ascorbic acid. The devil is in the details with L-ascorbic acid (or its derivatives), so remember to scrutinise the ingredient list of your skincare.The previous difficulties and limitations with L-ascorbic acid have now been overcome so there should not be an excuse for using derivatives.


For vitamin C or L-ascorbic acid to have an appreciable effect on your skin, the minimum effective concentration is 8%4. As the concentration of L-ascorbic acid increases, the effectiveness increases, up to 20%1,4. Beyond 20%, any additional benefit is negligible and the increased concentration might even cause skin irritation. So, look for L-ascorbic acid concentrations between 10% to 20% for best results! As for L-ascorbic acid derivatives, the idea concentration is still unknown due to a lack of rigorous trials and clinical data9.


Besides the type of vitamin C (i.e. L-ascorbic acid versus vitamin C derivatives) and the concentration of the vitamin C (ideally 10-20%), look for vitamin C formulations that also contain vitamin E and Ferulic. The addition of these two antioxidants have been found to result in a fourfold increase in protection against UV induced skin damage5,6.



Most vitamin C/L-ascorbic acid topical formulations are in the form of a serum or moisturiser. A basic sequence would be facial cleanser-serum-moisturiser-sunscreen (in the day). To learn more about how to build a skincare routine and the essentials that you need, check out my post The Biggest Skincare Mistake: 10/12/14 Step Skincare Routines.


One of the difficulties encountered with formulating skincare is getting into the skin. Our skin protects our bodies from water loss and penetration of harmful substances and that presents a challenge in allowing vitamin C/L-ascorbic acid to penetrate the deeper layer of the skin (dermis) where the cells that produce collagen (fibroblasts) and melanin (melanocytes) are located.


The top layer of the skin, called the epidermis, is designed to minimise loss (and as a result, also the uptake) of water. This presents an obstacle to vitamin C/L-ascorbic acid because vitamin C is a water-soluble vitamin that needs to be dissolved in water. However, by pre-treating the skin with lasers, chemical peels; the absorption of vitamin C through the skin can be enhanced10.


Related posts: The Truth About Chemical Peels and

10 Things to Know Before Having Lasers for Your Pigmentation.



You might ask about taking high doses of oral vitamin C; but only a small fraction of vitamin C will be available and active in the skin11. Hence, vitamin C in skincare and as part of a Skinboosters cocktail are preferred.


Intravenous vitamin C drips in Singapore for whitening is a controversial topic. Although these intravenous vitamin C drips or intravenous vitamin drips are performed in countries such as Taiwan and the US (celebrities Cara Delevingne, Rihanna and Barbie Hsu are reported to be fans of these vitamin C drips); intravenous vitamin drips for whitening and aesthetic purposes are banned by the Ministry of Health in Singapore.

These vitamin drips are known as intravenous micronutrient drips and the report benefits of these vitamin drips include: • Strengthened immune system • Improved energy levels • Improved nutrition • Faster recovery from illnesses

These benefits have been attributed to the higher levels of vitamin C in the blood that can be achieved with intravenous vitamin C than can be achieved with consuming vitamin C from food and supplements because these micronutrients are delivered directly into the blood; bypassing the absorption barrier in the gastrointestinal tract.

The use of high doses of intravenous vitamin C as a complementary treatment for cancer is currently being studied and the results have shown to be promising so far12. However, the use of intravenous vitamin drips for aesthetics in Singapore, especially for lightening complexion remains controversial as the safety and efficacy of these intravenous vitamin C drips lack sufficient data to support its use in Singapore. More about skin lightening drips in my review on Whitening Drips and Skin Bleaching Treatments.

Image credit: Newsweek


Covid-19 Update April 2020

Do Intravenous (IV) Vitamin C Drips Cure Covid-19 infections?

The use of intravenous vitamin C drips to treat infections including the flu has been controversial. Intravenous (IV) vitamin C drips deliver larger amounts of vitamin C directly into the bloodstream, as opposed to consuming oral vitamin C supplements that may not be 100% absorbed by the gastrointestinal tract.


Most of you might have heard of the advice to take vitamin C if you are unwell. The popularity of this piece of advice rose in the 1970’s when Nobel Prize winner, Dr Linus Pauling, advocated consuming vitamin C as a cure for cold. This quickly took off because it seemed to be an easy and cost effective way to strengthen one’s immunity against the cold. Now that the global spread of Covid-19 (Coronavirus) has reached unprecedented levels in modern times and there is still no cure or vaccine against Covid-19 in sight; high doses of intravenous vitamin C seem to be making a comeback in the news.

The big question is: Do IV vitamin C drips cure covid-19 infections? The short answer is no; that has yet to be proven. Research on the effect of IV vitamin C drips and the cold have also been equivocal and so the role of IV vitamin C drips in treating colds, infections and Covid-19 is not a part of mainstream treatment. There are currently trials underway to study the effects of IV vitamin C in infections, including whether IV vitamin C reduces the severity of infections.



I’ve covered Skinboosters in this post; and Skinbooster brands like Teosyal RD 1 contain Vitamin C, glutathione for additional brightening, antioxidants and anti-aging benefits on top of the deep skin hydration provided by the Skinboosters. In my practice, I also personalise a Skinbooster with additional ascorbic acid and glutathione and sometimes, Botulinum toxin (Botox) for added lightening, anti-aging and pore-refining properties.

In Singapore, Skinboosters with vitamin c and glutathione is an approved medical procedure.


In summary, vitamin C/L-ascorbic acid is a potent antioxidant that protects the skin from UV rays, lightens pigmentation and building collagen in the skin. Topical use of vitamin C is also very safe, making it a popular choice for dermatologists and skincare companies in anti-aging skincare and as a supplement to clinic treatments.

The only form of vitamin C that can bring about benefits to the skin is L-ascorbic acid, so remember to scrutinise the ingredient list of the skincare that you purchase. An effective concentration to choose from would be between 10-20%. Including vitamin E and ferulic in the vitamin C formulation also increases the efficacy of topical vitamin C. I would not recommend using any of the derivatives because they do not act on the skin and the conversion back to L-ascorbic acid if at all, is unknown. My gold standard picks that meet these criteria for best results Drunk Elephant’s C Firma and Skinceuticals’ CE Ferulic. Both contain 15% L-ascorbic acid, 1% vitamin E and 0.5% Ferulic.

One of my roles I enjoy as an aesthetic doctor (besides treating patients and educating the public) is helping my patients choose the right skincare for their skin type and conditions. I find that good anti-aging and antioxidant skincare (and by good, I mean that the formulation stands up to scrutiny and is backed by science) can sometimes be costly or hard to get in Singapore (i.e. you have to ship it in form overseas). My patients will know that I have affordable skincare recommendations including some of my drug store favourites. Your daily skincare habits and routine is essential in maintaining the results of your treatments and protecting your skin and I feel that there is no one ‘best’ skincare product out there that works for everyone and there are economical options out there for the rest of us would do not wish to splurge. More on my economical/drug store favourites in another post!

My vitamin C serum, formulated by me. 20% L-ascorbic acid, 1% vitamin E and 0.5% Ferulic for maximum efficacy, skin penetration and stability.

Shifting the focus of this post to a little project I’ve been working on for 8 months now; my own vitamin C serum that I’ve formulated after countless revisions (and rejections). One the perks of my job is creating and curating skincare that I would use for myself and sharing it with my patients. My vitamin C serum contains 20% L-ascorbic acid, 1% vitamin E and 0.5% Ferulic. The pH of this serum is 2.8, allowing for maximum skin absorption and efficacy. I also included in arbutin, another pigmentation lightening ingredient and hyaluronic acid for hydrating benefits.

Last week at the launch of my skincare line that’s based on the philosophy that taking care of your skin should be straightforward, backed by science and achieve maximum utility in the shortest time possible. If you know me, you would also realise that is my philosophy at work too.

The great thing is that I have a laboratory that I work closely with that allows me to manufacture this serum in small batches for maximum ‘freshness’. The packaging may look nondescript and boring but this airless bottle does not allow any air in (and hence, free radicals in the air) to oxidise the L-ascorbic acid. The opaque bottling also protects UV rays from damaging the vitamin C ensuring the shelf life is maintained.

My vitamin C serum retails for $135 in my clinic, La Clinic.

So there you go, all the essentials of vitamin C in dermatology and how to pick a vitamin C product if you would like to include it in skincare routine!

References 1. Cosmetical Vitamins: Vitamin C. In: Draelos ZD, Dover JS, Alam M, editors. Cosmoceuticals. Procedures in Cosmetic Dermatology. 2nd ed. New York: Saunders Elsevier; 2009. pp. 51–56. Farris. 2. Topical Vitamin C and the Skin: Mechanisms of Action and Clinical Applications. Niaimi and Chiang. J Clin Aesthet Dermatol. 2017 Jul; 10(7): 14–17. 3. Vitamin C in Dermatology. Telang. Indian Dermatol Online J. 2013 Apr-Jun; 4(2): 143–146.. 4. Topical L-ascorbic acid: percutaneous absorption studies. Pinnell et al. Dermatol Surg. 2001;27(2):137–142 5. Ferulic acid stablizes a solution of vitamins C and E and doubles its photoprotection of skin. Lin et al. J Am Acad Dermatol 2003; 48: 866–74. 33 6. Ferulic acid stabilizes a solution of vitamins C and E and DOUBLES its photoprotection of skin. Lin et al. Soc Investig Dermatol 2005; 125: 826–32. 7. Cosmeceuticals. Talakoub et al. Cosmetic dermatology. Vol. 1. Requisites in Dermatology. 1st ed. Gurgaon: Saunders Elsevier; 2009. pp. 13–4. 8. Use of Topical Ascorbic acid and its effects on Photo damaged skin topography. Traikovich. Arch Otorhinol Head Neck Surg. 1999;125:1091–8. 9. Stability, transdermal penetration, and cutaneous effects of ascorbic acid and its derivatives. Stamford. Journal of Cosmetic Dermatology, 11, 310—317. 10. Lasers and microdermabrasion enhance and control topical delivery of vitamin C. Lee et al. J Invest Dermatol. 2003;121(5):1118–1125. 11. UVR-induced oxidative stress in human skin in vivo: effects of oral vitamin C supplementation. McArdle et al. Free Radic Biol Med. 2002;33(10):1355 –1362. 12. High Dose Vitamin C. National Cancer Institute.




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