Hyperpigmentation, in which parts of the skin get darker than the rest of the skin, can be unsightly, particularly on the face. Often, it is caused by sun damage, acne or heredity, but it can have other causes. Topical treatment is the least invasive and most affordable way to treat this condition. The most popular topical treatment for hyperpigmentation is bleaching cream. Hydroquinone is the most common ingredient in bleaching products, but Kojic acid is also used in some products. In Japan, Kojic acid products are preferred for treating hyperpigmentation.
See a dermatologist about your hyperpigmentation first. In some rare cases, hyperpigmentation can be a symptom of another disease or disorder that should be diagnosed. Providing a medical history should help your doctor determine what is causing your hyperpigmentation and what treatments may work for you.
Treat your skin with products that contain Kojic acid. The most common formulations are creams and soaps. The easiest place to find Kojic products is in the skin-care section of a department store, as they are not commonly carried in drug stores.
Clean skin before applying the Kojic acid product. It's best to use a gentle cleanser, as skin irritation can exacerbate hyperpigmentation.
Apply the Kojic acid product to just the darkened areas you want lightened. Kojic acid inhibits tyrosinase, which regulates production of melanin. Using the product on other areas will cause undesired lightening, called hypopigmentation.
Allow the product to soak into the skin before using any other skin products in the area. This helps ensure maximum effectiveness.
Continue to use the product for several months before evaluating the final results. Skin bleaches and brighteners act gradually. It may take as long as 6 months for the area to be lightened to your satisfaction.
Avoid getting Kojic acid products into your eyes or mucous membranes. If you do, flush them thoroughly with cool water. Skin irritation can result from using products that have Kojic acid in them. Watch out for dermatitis and erythema, as they are common side effects. Always use a broad-spectrum sunscreen when using bleaching products, as skin can become sensitive to the sun and hyperpigmentation can be worsened by UVA and UVB rays. Products with Kojic acid may not be strong enough to treat all forms of hyperpigmentation. You may need to consider more aggressive treatment with some persistent cases.