We all want beautiful skin, right? Well, we can all have beautiful skin, even when faced with a few blemishes here and there.  One of the main issues many people experience where the skin is concerned is – hyperpigmentation or what is better known as discolouration of the skin.  This is where the skin has a few different tones (usually darker than one’s complexion) as well as dark spots.  The discolouration or hyperpigmentation of the skin can be caused by several factors, including excessive exposure to the sun, hormonal changes and even medication.

However, there are ingredients available that have proven to be not only beneficial for hyperpigmentation but also for the management of acne.  One such is – kojic acid.  But what are its benefits to the skin, especially, hyperpigmentation? Let’s discuss!

You can read more about the skin in this article.

• Love the skin you’re in!

The Discussion

Hyperpigmentation of the skin is a result of 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 colour 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 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 at the dermis (middle layer ) of the skin.  Finally, mixed hyperpigmentation is a combination of both the superficial and deep and is usually a result of the overproduction of melanin at both the epidermis and dermis layer 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.

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.

Kojic Acid and the Skin:

• What is kojic acid
• What is melanin
• How does kojic acid work
• Kojic acid’s antiviral, antimicrobial and anti-fungal properties
• Side effects of kojic acid

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 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 formations 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 is most popular, as well as in lotions, creams, lotions 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.

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, a 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 Flulton, 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 persons experienced reduced pigmentation with the kojic acid formulation (28%) than with the hydroquinone formation (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 it relate to the topical treatment of hyperpigmentation, especially for those suffering from melasma. Additionally, it is recommended that formulation of this nature must 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.).

Additionally, long-term use may cause the skin to become more prone to sunburn or worst yet, cancers when used on damaged skin (Saeedi et al. 2019; D.S. Yoo, et al. 2010l; 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?

Editor’s Note: Article updated on July 27, 2024.