100 women with epidermic melasma who were referred to the dermatology department of the 22 Bahman
Hospital in Mashhad were used in this clinical trial. Each patient had at least two melasma lesions of similar
severity and size on both sides of the face. For each patient, kojic acid cream on one side of the face and
hydroquinone 2% cream on the other side of the face were prescribed. The researchers assessed the rate of
improvement over a three month period.