Kojic acid is a relatively new up and coming skincare ingredient. The reason for this, I believe, is because of the sudden interest in treating skin pigmentation conditions using acids.
What is Kojic acid?
In short, it’s a by-product of the aerobic process of carbohydrates.
However, this is a beauty blog, so that is probably not of interest to you. What’s more important to know, in this instance, is that it is used to treat skin pigmentation conditions.
It comes in a number of different forms including; serums, creams, cleansers, soaps and powders.
What does Kojic acid do to your skin?
It’s main benefits are centred around ‘skin-lightening’, which is why it’s so often recommenced to treat Melasma.
This is because it can inhibit tyrosinase, which is a protein that can be oxidised to produce (1) the molecule, melanin.
Hence, there has been lots of research to suggest that using this acid will result in less hyperpigmentation.
This study (2), from 2001, took forty women with epidermal Melasma and treated them with 2% kojic acid in a gel containing 10% glycolic acid and 2% hydroquinone on one half of the face.
The other half was treated with the same application but without kojic acid.
The results showed all patients showed improvement in melasma on both sides of the face.
The side receiving the kojic acid did better.
So, is it effective, this study would suggest it definitely is.
Can Kojic acid permanently lighten skin?
For this to be true, KA would have to be a non-reversible tyrosinase inhibitor.
At the moment, there isn’t enough research to suggest this is true. So, if you see improvements when using KA, the likelihood is that you’ll stop seeing them if you stop using KA.
Although, studies differ the general consensus is that it can help to lighten your skin and treat hyperpigmentation caused by an overproduction of melanin. However, you shouldn’t expect a miracle and you will only see a difference with consistent use.
Is Kojic acid better than hydroquinone?
This is very dependent on each individual. However, I will refer you to this study from 1996 (3), which directly compared the two.
In the study, thirty‐nine patients were treated with kojic acid on one side of the face and hydroquinone in a similar vehicle on the other side of the face.
Fifty‐one percent of the patients responded equally to hydroquinone and kojic acid. Twenty‐eight percent had a more dramatic reduction in pigment on the kojic acid side; whereas 21% had a more dramatic improvement with the hydroquinone formulation.
The study also indicated patients thought KA was more irritating.
If you have sensitive skin, the results above indicate you may be better of trying hydroquinone first.
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(1) Ren, X., Zou, Q., Yuan, C., Chang, R., Xing, R., & Yan, X. (2019). The dominant role of oxygen in modulating the chemical evolution pathways of tyrosine in peptides: dityrosine or melanin. Angewandte Chemie International Edition, 58(18), 5872-5876.
(2) Lim, J.T.E., Frcpi, and Fams, (1999), Treatment of Melasma Using Kojic Acid in a Gel Containing Hydroquinone and Glycolic Acid. Dermatologic Surgery, 25: 282-284. https://doi.org/10.1046/j.1524-4725.1999.08236.x
(3) Garcia, A., & Fulton Jr, J. E. (1996). The combination of glycolic acid and hydroquinone or kojic acid for the treatment of melasma and related conditions. Dermatologic surgery, 22(5), 443-447.