Kojic acid and vitamin C: How to use them together

Kojic acid and Vitamin C are two ingredients loved by dermatologists for the treatment of hyperpigmentation, dark spots, scars, and age spots caused by UV rays. While Vitamin C has been around for a long time, kojic acid is more recent on the beauty scene. More common in Korean beauty products it slowly gained popularity and has risen to the standard of the star ingredient. In this article, we learn all about both ingredients and how to use them together.

What is Kojic acid?

Kojic acid is a byproduct of the fermentation process of certain foods such as rice wine, soy sauce, and Japanese sake. It is essentially made up of various types of fungi and is principally used in the skincare industry for its skin brightening, and antioxidant properties. Because of its relatively new arrival on the beauty scene, not a lot of research is available on this acid. However, a 1999 study revealed when added to a gel containing 10% glycolic acid and 2% hydroquinone, the gel was more effective at clearing dark spots than the same cream without kojic acid. 

Vitamin C in skincare 

Vitamin C is one of the most widely known ingredients in the skincare industry. It is known for its high antioxidant activity which enables it to reduce oxidative stress on the skin. Vitamin C helps boost collagen formation for firmer skin. Vitamin C also has the capacity to fade dark and brown spots. It is recommended alongside other treatments for hyperpigmentation. 

When compared to Kojic acid, vitamin C is less effective. This is mainly due to the unstable nature of the vitamin C molecule which breaks down when exposed to air or light reason why is mostly formulated in serums.

Is it safe to use Kojic acid and Vitamin C together?

It is possible to use kojic acid together with vitamin C on your skin, however, if you have sensitive skin it is advisable to layer them separately in your routine.

Kojic acid is a very strong active ingredient and although considered safe to use on the skin in low concentrations, it can cause allergic reactions on sensitive skin. Therefore, unless you have sensitive skin, you can use both ingredients.

Some products combine both active ingredients in their formulation. A comparative study on various melasma treatments revealed that a  Kojic acid (3%)+Vitamin C (2%) cream was effective at improving discolorations on the skin after a hydroquinone+Tretinoin and an azelaic acid cream. 

How to use kojic acid and vitamin C together

To incorporate both for optimal results it is better to layer them separately in your routine. Apply kojic acid in your morning routine after your cleanser and toner and before your oily serums and moisturizer. Go in with your vitamin C serum in the evening before your moisturizer.

Both exist as serums and creams and the choice of which format to go for is based on your preference. Products like the PHB Ethical Beauty Superfood serum combine both kojic acid and vitamin C to revive and brighten the skin.

Benefits of kojic acid and vitamin C for the skin

Benefits of kojic acid

Benefits of vitamin C 

Side effects of Kojic acid and Vitamin C 

Kojic acid 

  • The potential risk that comes with the use of kojic acid is contact dermatitis or allergies that can cause skin irritation, redness, itchiness, skin inflammation, and pain. This is most likely to occur with sensitive skin types. 
  • Prolonged use of kojic acid may increase the skin’s sensitivity to the sun leading to sunburns.

Vitamin C 

  • Although mostly considered safe, it can irritate very sensitive skin. Always do a patch test before use. 
  • Some forms of vitamin C are very unstable and breakdown in contact with sunlight or air rendering products less effective