Patients' attitudes toward side effects of antidepressants are likely to differ according to gender, which has not yet been fully addressed in the literature. From the 228,310 registrants, 1,305 participants who had received antidepressant drugs within the past year were identified with the Yahoo Japan research monitor through four-step screening procedures. Participants were asked as to which side effect(s) they had experienced, whether they had reported those side effects to their physicians, and whether they had taken any action to counteract them. The questionnaire was completed by 1,187 participants. Side effects were reported in 73.4% of the participants; the prevalence of self-reported side effects was significantly higher in men than women (80.4% vs. 68.3%, P <0.05). The percentage of participants who reported side effects to their physicians widely differed depending on the nature of their experience, ranging from 45.7% to 89.9%; the lowest was for sexual dysfunction. The percentage of participants who had taken any action to relieve side effects varied among side effects from 26.3% for sexual dysfunction to 89.5% for dry mouth. Moreover, a lower percentage of women had reported sexual dysfunction to physicians (36.6% vs. 60.7%, P <0.05) and had taken any action to counteract the problem (19.8% vs. 36.9%, P <0.05). Given that patients experienced with antidepressants are likely to be reluctant to report sexual side effects, physicians should be cognizant of the potential presence of sexual dysfunction in patients who are taking antidepressants, especially for women.