Kojic Acid, a chelation agent, is extracted from certain fungi such as Aspergillus oryzae.
It was discovered in 1907 from this fungus which was grown on steamed rice, also known
as Koji, from which the acid gets its name. It is also a by-product found in Japanese cuisine in the production and fermentation of products using koji malt such as soy sauce, sake and miso. It is also used as a preservative for fresh vegetables and meat, and as an oxidant for fats and oils.
In the dermatological industry the use of Kojic was approved in 1988 and has become the standard treatment for skin lightening with worldwide recognition for its efficacy. As a skin lightening agent it has an effect on tyrosine, a protein amino acid found in the skin where it inhibits tyrosine’s ability to make the primary pigment in the skin known as melanin. By preventing melanin production and thus pigmentation, both skin colour and tone are lessened and thus lightened. Melanin affects eye and hair colour, as well as skin colour. However, the use of Kojic acid should only be used to treat hyperpigmentation or scarring, and is not recommended to be used to lighten a natural complexion.
The topical use of Kojic acid in cosmetic products is not only as a lightening agent. Besides reducing pigmentation, Kojic acid also produces anti-aging effects by reversing sun damage from sun spots, liver spots and freckles, and reducing wrinkles. UVA and UVB rays induce inflammation and trigger reactive oxygen species (ROS) which degrade collagen and cause aging signs in the skin. Kojic acid prevents this inflammation and inhibits ROS, while protecting the firmness and suppleness of the skin. In the aging process, normal skin tone tends to become a yellowish brown due to glycation, the bonding of proteins in collagen and carbohydrates. Kojic acid can significantly inhibit this process. In the latter conditions, the use of creams and lotions would be used in place of soaps.
Kojic acid’s anti-bacterial properties are effective against many strains of bacterial infections in acne cases and in some cases will help to lighten acne scar tissue that hasn’t yet faded.
Its anti-fungal properties are particularly helpful in the treatment of yeast infections such as athlete’s foot, ringworm and candidiasis. The regular use of Kojic acid soap may help in the prevention of both bacterial and fungal body infections. In general, Kojic acid is safe to use on most skins and the potential benefits outweigh the few side effects experienced by a few patients. The effects of contact dermatitis may manifest as redness, irritation, itchiness, rashes, swollen skin, pain and/or discomfort. These may appear in patients with very sensitive skins or those who use Kojic acid products which have a higher concentration than 1% of Kojic acid. In these cases, the use of Kojic acid products should be discontinued and over-the-counter hydrocortisone cream applied to the affected areas.
Hydroquinone can also be used to lighten skin but can be irritating and sometimes worsen the pigmentation instead of lightening it. Occasionally hydroquinone use results in a condition known as ochronosis which causes the skin to form papules with a blue/black pigmentation. A papule or skin lesion is a small area of abnormal tissue with distinct borders and various shapes which may form a rash if there is more than one lesion.
Kojic acid can be used after using hydroquinone first, allowing for continued lightening.
One of the prime uses of Kojic acid is during pregnancy when melasma occurs. This condition, also called chloasma or ‘the mask of pregnancy’, results in dark and discoloured patches forming on the skin, generally in the facial area, and sometimes on the forearms and neck. Melasma can also be caused from the taking of contraceptive medication.
Kojic acid products come in various forms such as powders, serums, creams, cleansers and soaps. Powders are mixed with either a lotion or water. Soaps and cleansers stay on the skin for a very limited amount of time, starting with 15-30 seconds and adding 15-30 seconds every two to three days until a maximum time of four minutes is reached. Creams and serums are left on to be absorbed by the skin and may be used daily. Face masks should only be used occasionally. Kojic acid products are usually used on the face and upper body, but may be used on any other non-sensitive body area. The using of Kojic acid products should show results within two weeks and in cases where glycolic acid is added to Kojic acid, may show an even faster result. Certain Kojic acid products also contain Papain; this natural exfoliant aids in the penetration of Kojic acid to the lower layers of the skin. In a few patients, results may only be seen after a few months, but in most people the results show within a few weeks.
The long term use of Kojic acid products may make your skin more likely to react to sunburn. The wearing of sun protection clothing and sunscreen creams should be taken seriously. Kojic acid products must never be used on broken or damaged skin areas.
In general, it is to your advantage to contact a dermatologist who will advise you whether or not Kojic acid products will help you, and a practitioner will advise you on how to use the products correctly for the best results. The use of Kojic acid products should not be continual – only use until the condition has healed or the desired results are seen.
Cosmetic products are not regulated in the way that medicines and foods are, but Kojic acid usage is safe provided that the concentration of Kojic acid does not exceed 2%, eliminating the possibility of skin irritations.