Kojic Acid

Fast Facts

Type of Ingredient: Skin lightener

Main Benefits: It is used to lighten the skin and treat skin conditions such as sun damage, scars, and age spots.

Who Should Use It: Kojic acid is most commonly used in cosmetic products such as creams, lotions, and serums. It is also used in some soaps. Many products with kojic acid are intended for use on the hands or face.

Ideal For These Concerns: Hyperpigmentation, sun damage, and dark spots

How Often Can You Use It: You can use it every day but can cause redness, irritation

What is Kojic acid?

Kojic acid is made from several different types of fungi. It’s also a byproduct when some foods ferment, including Japanese sake, soy sauce, and rice wine. Kojic acid hinders the production of tyrosine, which is an amino acid that’s required to generate melanin. Melanin is the pigment that affects hair, skin, and eye color. Because it inhibits the production of melanin, kojic acid can have a lightening effect.

The Benefits of Kojic acid

Kojic acid is usually used topically to treat various skin conditions but most often as a skin bleaching agent. It’s been recommended for use in cosmetic formulas in concentrations of 1 percent or less. Kojic acid can be seen in many different types of cosmetic products, including powders, serums, creams, cleansers, and soaps. Powders need to be mixed with water or lotion, depending on the product's directions. Some products, like soaps and cleansers, are intended to be washed off instantly. Others, like creams and serums, are designed to be left on and absorbed into the skin. (However, kojic acid overall has relatively poor absorption rates below the surface of the skin.)

Kojic’s acid primary benefit is to lighten visible sun damage, age spots, or scars. Along with its skin-lightening effects, kojic acid also has some antimicrobial properties. It may help fight off several common types of bacterial strains even in small quantities. This can help treat acne caused by bacteria in the skin. It can also lighten scars from acne that are less than a year old.

Kojic acid also has antifungal features. It’s even added to some antifungal products to improve their effectiveness. It may be beneficial in treating fungal infections such as yeast infections, candidiasis, and ringworm or athlete’s foot. If soap containing kojic acid is used regularly, it could help prevent both bacterial and fungal infections on the body.

SAFETY

The Cosmetic Ingredient Review Expert Panel concluded that kojic acid is safe to use in cosmetics in concentrations of 1 percent. However, some people may still experience side effects from their use. The Food and Drug Administration controls the quality and safety of cosmetics, so be sure to buy products from a trustworthy company in the United States.

Contact dermatitis is the most common side effect of kojic acid. It can display itself as redness, irritation, itchiness, rashes, swollen skin, or pain and discomfort. Contact dermatitis is most frequent in those with sensitive skin, or people using a product with a greater concentration than 1 percent of kojic acid. Discontinue use if you’re reacting to a product with kojic acid in it.

Over time, long-term use of kojic acid may make your skin more susceptive to sunburn. Make sure to always wear sunscreen. Make sure to never use kojic acid on damaged or broken skin. Some countries have banned this product because of a possible connection to the development of cancer. Further research is needed to identify and understand any other potential side effects.

References:

Arnett CL, et al. (2010). Final report of the safety assessment of kojic acid as used in cosmetics. DOI:
10.1177/1091581810385956
Cabanes J, et al. (1994). Kojic acid, a cosmetic skin whitening agent, is a slow-binding inhibitor of catecholase activity of tyrosinase. DOI:
ncbi.nlm.nih.gov/pubmed/7714722
Faig JJ, et al. (2017). Biodegradable kojic acid-based polymers: Controlled delivery of bioactive for melanogenesis inhibition. DOI:
10.1021/acs.biomac.6b01353
Kim JH. (2013). Synergism of antifungal activity between mitochondrial respiration inhibitors and kojic acid. DOI:
ncbi.nlm.nih.gov/pubmed/23353126