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Everything You Need to Know About Kojic Acid

Tanmay Tikekar
What is kojic acid? Why is it used in cosmetics? Does it have any side effects? Read on, if you want to know the answers to these queries.

Kojic acid by any other name...

The IUPAC name of kojic acid is 5-Hydroxy-2-(hydroxymethyl)-4H-pyran-4-one. It can also be labeled 5-Hydroxy-2-(hydroxymethyl)-4-pyrone and 2-Hydroxymethyl-5-hydroxy-γ-pyrone.
Kojic acid is an organic acid usually extracted from fungi. It is a chelation agent and is a common ingredient in skin-lightening products, such as fairness creams, soaps, and lotions.
It works by slowing down the formation of new pigments, which are responsible for the color of any organic object you see. With respect to cosmetics, it slows down the production of melanin. Melanin is responsible for darker skin tones.
Everyone has some amount of melanin, including white people, and it's the (genetically preordained) amount rather than the presence or absence of melanin that determines the individual's complexion. So when its production is hampered, the skin looks fairer, at least temporarily. Thus, it is actually one of the few foolproof ways of lightening your skin tone.
Kojic acid has medical uses as well. Melanin, or rather the overproduction of it, is also responsible for moles, freckles, and the like. When the secretion of melanin occurs or increases in patches rather than uniformly, moles or freckles occur. Medication containing kojic acid can also treat these.
It is also used as medication against pigment-related skin diseases such as melasma. It can also reverse sunburn. Another benefit for the cosmetic industry is the faint antimicrobial properties of kojic acid.
It is also used to keep cut fruits fresh, since it prevents a change in color. Similarly, it is also applied to seafood, such as fish meat and prawns, to preserve the fresh pink or red shades.
t is used in tooth-whitening products as well. However, it is not as effective in that context as in skin-lightening products, since the color of teeth is not determined by pigments.


Chemically speaking, kojic acid is a hydrocarbon (not to be confused with carbohydrates; consuming kojic acid won't provide you energy) in the class of pyrones or pyranones (thus the IUPAC name).
It has a molecular formula of C6H6O4. It is an unsaturated cyclical hydrocarbon, containing two instances of a double bond between carbon atoms. Here's an illustration of the molecular structure of kojic acid.

Side Effects and Risks

Though it is usually quite a safe chemical to use, there are some risks involved in its application. The likeliest risk is skin irritation, especially if the individual has a sensitive skin. Many people may feel a slight stinging sensation while applying kojic acid-containing products, but in most cases, the effect will soon fade away.
If you do have a sensitive skin, patch test a cosmetic product containing kojic acid, or consult your doctor. Large amounts of pure kojic acid are harmful if ingested, inhaled, or even topically applied.
These effects are kept in check in part by the small amount present in typical cosmetic products and by corticosteroids, which are often included in skincare products.
Prolonged application of kojic acid-containing products may lead to allergic contact dermatitis. This is manifested through symptoms such as itchy rashes, redness, and blisters. Stop using kojic acid-containing creams if you encounter this condition.
Melanin is responsible for protecting your skin and inner organs from harmful solar radiation. The comparatively lower amounts of average sunlight is the reason why most northern races evolved fairer skin, while people in the tropics or subtropical regions evolved melanin-rich darker skins to combat the harsh sunlight.
So, any product that lessens the amount of melanin increases your chances of getting sunburns or even skin cancer.