Background: No epidemiological study has examined the clinical characteristics, including medication use, of patients with eosinophilic pustular folliculitis (EPF). Objective: To describe the clinical characteristics for EPF and to examine the factors associated with the effectiveness of oral indomethacin for EPF. Methods: A cross-sectional study was performed of patients with EPF who visited the dermatology departments of the 67 main teaching facilities in Japan. We documented the patient characteristics and examined factors associated with the effectiveness of oral indomethacin. Results: A total of 145 patients with EPF were enrolled; 62.8% were prescribed oral indomethacin. A multivariable analysis revealed that female patients were more likely to exhibit complete response to oral indomethacin after adjustment for confounders (adjusted proportion ratio = 1.93, p = 0.04). Conclusion: Oral indomethacin has been accepted as a first-line treatment in EPF. Our results suggest that there is a sex difference in the treatment response to oral indomethacin. (C) 2014 S. Karger AG, Basel