Ingredient spotlight: Kojic acid

A sunny day at the beach is a blast. The ensuing dark spots and skin damage? Not so much. Fortunately, there are proven effective ingredients available, such as kojic acid, that may help combat hyperpigmentation.

Kojic acid is a naturally derived ingredient used to help fade dark spots and even skin discoloration from sun exposure, melasma, and post-inflammatory hyperpigmentation. This ingredient is effective on its own or can be combined with other ingredients for a synergistic effect.

Here we’ll shed some light on kojic acid, how it works, its potential benefits and side effects. We’ll also list ingredients it pairs well with to achieve the best results. 

What is kojic acid?

Kojic acid is a chemical product sourced from mushrooms. It’s also present in the fermentation of rice wine and soy sauce.¹

Most acids used in skincare exfoliate, but kojic acid has a different function. It inhibits tyrosinase, an enzyme needed to produce melanin.² Melanin is a naturally occurring pigment that gives skin, hair, and eyes their color. By blocking melanin production, kojic acid has a brightening effect when applied to the skin. It may help reduce visible dark spots from sun damage and discolored areas of the skin, including melasma and post-inflammatory hyperpigmentation (PIH). 

Potential benefits of kojic acid for skin

Kojic acid serums, creams, and lotions are used on the hands, face, and other areas with uneven skin tone to treat hyperpigmentation. It’s commonly used in skincare products to treat sun damage, signs of aging, and skin conditions like melasma. 

Here are a few of the potential benefits of kojic acid: 

• It may help reduce melanin production. Melanin, which gives skin its color, is produced with the help of tyrosinase. Kojic acid inhibits tyrosinase activity, treating dark spots at the source.³

• It treats melasma. This skin condition appears as symmetrical darkened skin usually seen on the cheeks, upper lip, chin, and forehead. It often occurs during pregnancy, and it may fade on its own or last for years.⁴ Research shows that kojic acid is an effective treatment option for melasma.⁵

• It may help improve post-inflammatory hyperpigmentation (PIH). PIH occurs when melanocytes (melanin-forming cells) produce too much melanin in response to inflammation, injury, or certain medical procedures.⁶ In much the same way kojic acid helps minimize the appearance of other types of dark spots, it also helps reduce the appearance of PIH.⁷

Is kojic acid safe?

Kojic acid is included in all sorts of products, including topical powders, serums, creams, cleansers, and soaps. Depending on the product, kojic acid is either rinsed off (cleansers and soaps) or left to absorb into the skin (powders, serums, and creams).

Some kojic acid products are fine to use daily, while others are to be used weekly or on occasion, such as kojic acid face masks. Regardless of how often it is used, there are some potential side effects: 

• Photosensitivity. Kojic acid may increase the skin’s vulnerability to sunburn over time, so always apply a broad-spectrum sunscreen with SPF 30 or higher (that said, this should already be part of your daily skincare ritual!).⁸

• Contact dermatitis. More common in those with sensitive skin, contact dermatitis symptoms may include redness, irritation, itchiness, rashes, inflammation, pain, and discomfort.⁹

• Dryness and irritation. This ingredient pairs well with other skincare ingredients to increase its effectiveness, but using too many ingredients at once may cause dryness and skin irritation. It’s best to start off by using kojic acid alone before adding other active ingredients to see how your skin adjusts. 

Pairing kojic acid with other skincare ingredients

A key kojic acid benefit is its versatility. It mixes and matches well with other ingredients, such as hydroquinone, azelaic acid, and vitamin C. 

• Hydroquinone is the gold standard for treating dark spots and other types of hyperpigmentation. It’s available by prescription only. Kojic acid and hydroquinone combined demonstrated a superior depigmenting effect than other ingredients in one study.¹⁰

• Azelaic acid reduces redness and hyperpigmentation. Like kojic acid, it inhibits tyrosinase. Together, this duo has double the power to reduce the appearance of dark spots and other skin pigmentation concerns. 

• Vitamin C is a potent antioxidant proven to help protect the skin against signs of aging—especially from UV exposure.¹¹ It’s a popular ingredient in skin-brightening and anti-aging creams and serums. 

Customized skincare by Curology

Curology’s goal is to provide personalized skincare that’s accessible. Our licensed dermatology providers work with you to examine your skin, assess your skincare goals, and provide custom treatment options. Our products are formulated using clinically researched ingredients to help treat your skin concerns. 

Signing up is easy. Just answer a few questions and snap a few selfies to help us get to know your skin better. If Curology is right for you, an in-house dermatology provider will create a personalized prescription formula that targets your skin concerns.* They’re available to answer any skincare questions and modify your formula as your skin’s needs naturally shift over time.

P.S. We did the homework so you don’t have to:

1.  Saeedi, M., et al. Kojic acid applications in cosmetic and pharmaceutical preparations. Biomedicine and Pharmacotherapy. (February 2019).

2.  Saeedi, M., et al. Kojic acid applications in cosmetic and pharmaceutical preparations. Biomedicine and Pharmacotherapy. Ibid. 

3.  Saeedi, M., et al. Kojic acid applications in cosmetic and pharmaceutical preparations. Biomedicine and Pharmacotherapy. Ibid.

4.  American Academy of Dermatology. Melasma: Overview. (n.d.).

5.  Bandyopadhyay, D. Topical treatment of melasma. Indian Journal of Dermatology. (October-December 2009). 

6.  Silpa-Archa, N., et al. Postinflammatory hyperpigmentation: A comprehensive overview: Epidemiology, pathogenesis, clinical presentation, and noninvasive assessment technique. Journal of the American Academy of Dermatology. (2017).

7.  Saeedi, M, et al. Kojic acid applications in cosmetic and pharmaceutical preparations. Biomedicine & Pharmacotherapy, Volume 110. (2018 December 6).

8.  Saeedi, M, et al. Kojic acid applications in cosmetic and pharmaceutical preparations. Biomedicine & Pharmacotherapy, Volume 110. Ibid.

9.  Saeedi, M, et al. Kojic acid applications in cosmetic and pharmaceutical preparations. Biomedicine & Pharmacotherapy, Volume 110. Ibid.

10.  Deo, K.S., et al. Kojic acid vis-a-vis its combinations with hydroquinone and betamethasone valerates in melasma: A randomized, single blind, comparative study of the efficacy and safety. Indian Journal of Dermatology. (July-August 2013).

11.  Al-Niaimi F., et al. Topical Vitamin C and the Skin: Mechanisms of Action and Clinical Applications. The Journal of Clinical and Aesthetic Dermatology. (July 2017). 

* Subject to consultation. Subscription is required. Results may vary. 

Elise Griffin is a certified physician assistant at Curology. She received her Master of Medical Science in physician assistant studies from Nova Southeastern University in Jacksonville, FL.

Written by

Curology Team

Medically reviewed by

Elise Griffin, PA-C