Most of the guidelines for the treatment of major depression recommend the use of antidepressants for 4 to 8 weeks. On the other hand, it has been recently reported that they start to show their antidepressant efficacy within a couple of weeks (1,2), contrary to the conventional theory. In addition, a good response (i.e. a 20% reduction in the Montgomery-Åsberg Depression Rating Scale [MADRS]) at week 2 is proposed to be a predictor of subsequent remission at week 6 (3,4), while nonresponse at week 2 could predict unfavourable outcome at week 8 (5). Furthermore, early worsening is suggested to be related to a low rate of remission at weeks 8 and 12(6).