Kojic acid is a naturally occurring antibacterial and antifungal substance found in certain fungi and plant sources. Kojic acid is commonly used in skin care cosmetic products to lighten hyperpigmentation, pregnancy masks and other skin disorders. Long term use of kojic acid soap has revealed significant findings of hypersensitivity, allergic contact dermatitis and other skin irritations.
Skin Irritation
According to the Materials Safety Data Sheet prepared by Oxford University, kojic acid, which is the base of kojic acid soap, may be toxic if inhaled, ingested or absorbed into the skin. The skin is the body's largest organ, and 60 percent of what is applied topically is absorbed into the blood stream. The side effects of kojic acid soap increase if the kojic acid is exposed to oxidative agents; chlorine, peroxide and oxygen are all examples of oxidative agents.
Hypersensitivity
Long-term use in high dosages of kojic acid can cause hypersensitivity in those with very sensitive skin. According to kojicacid.org, the best way to reduce sensitivity to kojic acid is to use a topical corticosteroid to offset some of the effects. If you develop an allergic reaction, immediately stop using the kojic acid soap and contact a dermatologist for an evaluation.
Allergic Contact Dermatitis
Allergic contact dermatitis is the immune response to an allergen that comes in contact with the skin. Kojic acid soap may cause allergic contact dermatitis if used for prolonged periods.
Dry Skin
Kojic acid soap may cause skin dryness when used often; because the ingredients in kojic acid vary with each distributor, it is important to perform a patch test on the inside of the elbow to determine if the product will cause dryness or irritation before applying it to your face.
Sun Damage
Because kojic acid soap inhibits the tyrosinase enzyme; a key element in melanin synthesis, it hinders the production of melanin, which is necessary for preventing sun damage. Kojic soap should be used with sun block with an SPF 15, 20 or 30 for protection.
Cancer Risks
Kojic acid soap and kojic acid products are being researched for the possibility of carcinogens; the product is not to be used by those who are pregnant or those who may become pregnant due to the ongoing research of carcinogenics in kojic acid.
