Background: Melasma continues to be a difficult problem. Although the cause is genetic, the condition is aggravated with sunlight, birth control pills, and pregnancy. Although hydroquinone is effective and has been available for years, a new product, kojic acid, has the advantage of being pharmaceutically more stable and, also, a tyrosinase inhibitor.
Objective: To evaluate on melasma and related conditions two similar formulations of glycolic acid/hydroquinone and glycolic acid/kojic acid. The therapeutic index of the two formulations is examined.
Methods: 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. The results were documented by a clinical investigator and with Wood's light examination combined with ultraviolet light photography.
Results: 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. These results were not statistically different. The kojic acid preparation was more irritating.
Conclusion: Both glycolic acid/kojic acid and glycolic acid/hydroquinone topical skin care products are highly effective in reducing the pigment in melasma patients. Both formulations should be available to the dermatologist to satisfy the patient's preferences.