Methodological problems in the estimation of the onset of the antidepressant effect

The onset of activity of antidepressants is an aspect of their efficacy which is of practical as well as theoretical importance. Using MEDLINE a review of the literature published since 1975 was carried out in order to find out if a specific pattern can be observed. The authors point out what problems are most often encountered and illustrate the most common pitfalls. In the absence of a straightforward onset estimation, indirect arguments prevail which have several shortcomings. Methodological problems make it impossible to draw a clear conclusion.