Clear, healthy-looking skin is something many people desire. Yet one of the most common concerns in skincare is hyperpigmentation — areas of darkened skin that appear uneven compared to the surrounding complexion.

Hyperpigmentation, often referred to as skin discolouration, can present as dark spots, patches, or uneven tone. It may result from excessive sun exposure, hormonal changes, inflammation from acne, or certain medications. While generally harmless, it can affect confidence and overall skin appearance.

Fortunately, several topical ingredients have been studied for their ability to help reduce the appearance of dark spots and uneven tone. One such ingredient is kojic acid.

But what exactly is kojic acid, and how effective is it for managing hyperpigmentation?

In this article, we explore what kojic acid is, how it works, its potential benefits, and important safety considerations. Let’s discuss!

You can read more about the skin in this article.

• Love the skin you’re in!

What is Kojic Acid?

Kojic acid is described as an organic acid that is derived from the fermentation of various types of fungi, including Aspergillus and Penicillium (Lage and Costa, 2012).  The aspergillus fungus reportedly originates from Japan and is called ‘koji’, hence the name ‘kojic acid.’ (Saeedi et al., 2019; Saraei et al., 2016).   The acid was first isolated and named kojic acid in 1907 by the Japanese microbiologist K. Saito (Uher et al. 2007; Morton et al. 1945;  Burnett et al. 2010).  

Its main use then and now is managing hyperpigmentation or discolouration of the skin.  As such, it is generally marketed as an agent for skin depigmentation.  Kojic acid is not only popular in the cosmetic industry, but also in other industries such as pharmaceuticals and even agriculture (Saeedi et al. 2019).

Kojic acid can inhibit the formation of melanin due to its ability to prevent the activities of the enzyme tyrosinase (Saeedi et al. 2019; Mohiuddin, 2019).  Tyrosinase is an important enzyme that is required for the biosynthesis of melanin (Saeedi et al. 2019).   It also reportedly has low stability.  Therefore, it is very sensitive to light and heat and possesses oxidative properties (Ephrem et al. 2017; Balaguer et al. 2008).  However, to prevent the oxidation of kojic acid, other formulations of the acid are usually recommended, such as kojic acid dipalmitate and monooleate (Zaid, 2019; Hatem et al., 2020).

Importantly, kojic acid has been recognized by the Food and Drug Administration (FDA) to be used in cosmetics, particularly as an alternative to the once-famous hydroquinone, which is currently banned in Europe (Saeedi et al. 2019).  However, research has shown that kojic acid and hydroquinone have a synergetic effect when it comes to fighting inflammation and depigmentation (Meybeck, 1988).  Hence, its recommendation as a ‘perfect’ substitute for kojic acid.

You can find kojic acid in soap formats, which are most popular, as well as in lotions, creams, and even serums, among others. The typical concentrations usually range from 1 – 3%. However, most research suggests 1% or less to still be beneficial, not only for great results but for safe use, especially over the long term.

In this article, we will explore kojic acid (what it is) and how it helps with hyperpigmentation. We will also discuss its side effects and other noted benefits, especially the management of acne. The article will also provide useful links to other articles about the skin and ingredients that can help maintain its health, both in the short and long term.

You can read more on the skin and Alpha Hydroxy Acids (AHAs)  in these posts.

• Love the skin you’re in!

• Glycolic acid – The Sting of Beauty!

• Lactic acid and the Skin.

What is Hyperpigmentation?

Hyperpigmentation of the skin is a result of the disruption of the synthesis of melanin or the improper distribution of it, as per dermatologists (Nautiyal and Wairkar, 2021).  It usually presents itself as dark-coloured spots, darker than an individual’s skin tone (Nautiyal and Wairkar, 2021).   It may also be described as one having a darker skin tone, which is usually due to the accumulation of pigments, especially in areas that have been constantly exposed to the sun.

Reportedly, there are several layers or degrees of hyperpigmentation,n namely, superficial, deep (dermal) and mixed (Park et al. 2017; Vashi et al. 2017, etc.).   Superficial hyperpigmentation occurs at the epidermis level of the skin (first/top layer of the skin) and is typically a result of the overproduction of melanin. The deep or what is called dermal hyperpigmentation is usually a result of excessive melanin accumulation in the dermis (middle layer ) of the skin.  Finally, mixed hyperpigmentation is a combination of both the superficial and deep layers and is usually a result of the overproduction of melanin at both the epidermis and dermis layers of the skin (Park et al. 2017; Vashi et al. 2017, etc).

Importantly, before the administration of treatment for hyperpigmentation, your dermatologists may assess the skin to ensure that it is not melanoma (skin cancer).  Once it is not, then a plan of action may be implemented to treat the hyperpigmentation.  The usual procedures include chemical peel and microdermabrasion.  These may be structured over several periods.   

Alpha hydroxy acids (AHAs) may also be recommended, such as glycolic acid, lactic acid and azelaic acid. These are common acids you will find in topical cosmetic products, especially those geared at hyperpigmentation. However, there is a rising star ingredient that has been proven to help with hyperpigmentation – kojic acid. This ingredient, when used properly, can assist in eliminating hyperpigmentation, especially when combined with other products and ingredients (AHAs) as a skincare routine.

You can read more on another ingredient that has been proven to help with hyperpigmentation in this article:

• Oh, So Bright – Six (6) Skincare Benefits of Vitamin C and how to add it to your Skincare Regimen

What is Melanin?

Melanin is reportedly a large group of related molecules that is responsible for the pigmentation of the skin and hair (Maranduca et al. 2019; Fernandez-Flores et al. 2019, etc).  It is also responsible for other biological functions of the body, such as photoprotection of the skin and eyes (Maranduca et al. 2019; Fernandez-Flores et al. 2019, etc.).

There are three (3) different forms of melanin the human body produces – eumelanin, phenomelanin and neuromelanin (Schlessinger et al. 2024).  The eumelanin form of melanin is further divided into black and brown.  Eumelanin and pheomelanin are produced in varying amounts in the epidermis layer of the skin within cells known as melanocytes (D’Alba and Shawkey, 2019). The neuromelanin is a dark pigment that is produced by cells known as dopaminergic and noradrenergic (Del Bino et al. 2018).

When the body produces melanin, it is stored in small membrane-bound organelles called melanosomes. These then further travel to keratinocyte cells, which work to protect the skin from ultraviolet radiation (D’Alba and Shawkey, 2019).  Membrane-bound organelles are described as cellular structures that are bound by a particular biological membrane (study.com).  Examples include the mitochondria, nucleus, etc.  As such, melanin protects the skin against Ultraviolet (UV) radiation.  

Notably, pigmentation of the skin is regulated by several factors, including genetics, hormones and the environment, and manages the distribution of melanin in the skin (D’Mello et al. 2016; Wawrzyk-Bochenek et al. 2023).   The tyrosinase enzyme, which is found in kojic acid, works at the molecular level of the skin to fight hyperpigmentation (Del Bino et al. 2018).

How Does Kojic Acid Work?

Kojic acid is reportedly derived from various fungi and is used to reduce hyperpigmentation or discolouration of the skin.  This is done by inhibiting the formation of tyrosinase, an enzyme critical for the biosynthesis of melanin (Saeedi et al. 2019; Mohiuddin, 2019).  Principally, almost all products that are geared at reducing hyperpigmentation aim to reduce the activities of the enzyme – tyrosinase.

However, kojic acid is considered one of the most effective in reducing hyperpigmentation, sun damage and age spots (Draelos, 2007).  As such, it is usually regarded as an effective skin-lightening agent (Aytemir and Karakay, 2012).  In addition to its natural skin-lightening potential, kojic acid also reportedly has antioxidants, anti-inflammatory (Van Tran et al. 2018; Brtko et al. 2004) and antifungal properties (B.S. Reddy et al. 2010).   It is also anti-acne (R.B. Aronsohn, 1986) and may provide antiaging outcomes, as well as being beneficial in treating infections such as yeast, ringworm and candidiasis (J.E. Nett et al., 2008).

Kojic Acid Antiviral, Antimicrobial and Anti-fungal Properties

In addition to its depigmentation benefits, kojic acid reportedly has antimicrobial properties.  Both its antibacterial and anti-biofilm activities may help against several foodborne pathologies such as Listeria monocytogenes, Escherichia coli, Salmonella Typhimurium, etc (Wu et al. 2019).  

According to researchers, the antimicrobial properties of kojic acid may play a significant role against gram-negative bacteria (?) and be able to inhibit the formation of biofilm that is usually caused by these bacteria (Wu et al. 2019).  Reports also contend that it possesses anti-fungal properties, which makes it even more beneficial for overall skin care.

Kojic acid’s antimicrobial properties have also been proven to eradicate some of the common types of bacterial strains that can cause acne, even in small amounts (Saeedi et al. 2019).

Can Kojic Acid and Glycolic Acid Be Used Together?

The simple answer, based on research, would be ‘Yes.” Nonetheless, it is usually not recommended that certain acids be paired or used together due to the possibility of over-exfoliation and other skincare issues, particularly for sensitive skin.  However, research by Garcia and Fulton in 1996 showed that Kojic acid could be paired with both glycolic acid and hydroquinone for effective results, especially for those suffering from melasma (Garcia and Fulton, 1996).

In this study, the researchers used a formulation of either glycolic acid/hydroquinone or glycolic acid/kojic acid.  Thirty-nine (39) persons participated in the study. Both formations were used, with one being applied to one side of the face and the other to the next side. A little over half of the participants (51%) experienced similar results with both formulations. 

However, more people experienced reduced pigmentation with the kojic acid formulation (28%) than with the hydroquinone formulation (21%). Nonetheless, the kojic acid formulation was stated to be more irritating than that of the hydroquinone.

Notwithstanding, the researchers concluded that both formulations are worthwhile considerations for dermatologists as they relate to the topical treatment of hyperpigmentation, especially for those suffering from melasma. Additionally, it is recommended that formulation of this nature be done under the supervision of a dermatologist.

You can read more on glycolic acid and the skin in this article:

• Glycolic Acid – the Sting of Beauty!

What are the Side Effects of Kojic Acid?

Some adverse effects have been observed with the use of kojic acid, such as contact dermatitis, especially in sensitive skin, irritation, rashes, itchiness, inflamed skin and even pain (Saeedi et al. 2019).  However, most of these side effects have been observed with concentrations higher than 1%. 1% is the typical recommended percentage.  

Studies have shown beneficial results in topical application of 1% or less, as well as being safe  (P. Elsner and Maibach, 2000).  Further, patients who were suffering from melasma used a 1% cream for two (2) years with no significant adverse effects or reactions (M. Nakagawa et al. 1995; A. Breathnach, 1996, et al.).

Additionally, long-term use may cause the skin to become more prone to sunburn o,r worst yet, cancers when used on damaged skin (Saeedi et al. 2019; D.S. Yoo et al. 2010; E. Guibal, 2004).  As such, it is recommended that you wear sunscreen when using products with kojic acid.  It is also recommended that you do not use it on damaged skin. 

You can read more on the skin and sunscreen in these articles below:

• Love the skin you’re in

• What are Sunscreens – Benefits and Ingredients to look out for when purchasing?

Illustrative Summary

Here is an illustrative summary of KOJIC ACID BENEFITS  AND SIDE EFFECTS.

Let’s Sum Up!

Many ingredients have been studied for hyperpigmentation and/or discolouration of the skin.  Kojic acid is one such ingredient.

Kojic acid has been proven to act as a brightening ingredient as well as help with acne due to its antimicrobial properties.  As such, if you suffer from hyperpigmentation, melasma, etc., then this might be an ingredient to consider as part of your skincare arsenal.

Remember, kojic acid must be used with care and preferably under the supervision of a dermatologist, especially if you suffer from severe hyperpigmentation. This is due to its reported side effect such as contact dermatitis, sunburn or even cancers, when used on damaged skin, and over a long period.

So, do you suffer from hyperpigmentation or other skin conditions that cause discolouration of the skin? Will you be using Kojic acid?  Share it in the comments section below.

You can learn more about the skin, sunscreen and acne care by reading the articles below:

1. Glycolic acid – the Sting of Beauty!

2. Benzoyl Peroxide Vs. Salicylic Acid for Acne

3. Love the skin you’re in

4. What are Sunscreens – Benefits and Ingredients to look out for when purchasing?

5. Video: Let’s Talk Kojic Acid
   

Editor’s Note: This article was last updated by a Research Consultant and Certified Nutrition Coach on February 25, 2026.