Seventy patients (50 with melasma, 10 with freckles, and 10 with post-inflammatory hyperpigmentation) were admitted to this trial. Treatment in the form of 4% hydroquinone (HQ) was applied topically twice daily for a maximum of 12 weeks. Patients were advised to avoid sun exposure and/or to use topical sunscreen during the entire period of treatment.

All patients were examined at week 0 and at weeks 4, 8, and 12 of therapy. At each visit, the lesion size was determined and the pigmentary intensity of melasma, freckles, and the area of post-inflammatory hyperpigmentation (PIH) relative to a non-affected area of skin was rated on a four-point scale: 1, no difference; 2, mild pigmentation; 3, moderate pigmentation; 4, severe pigmentation. At the last visit, the overall response was rated as excellent, good, fair, or poor.