Considering the pathophysiology of depression, we may talk about the alteration of several receptors, enzymes, neurotransmitters or secondary messengers. Current antidepressants are thought to act by restoring these alterations. Despite having different mechanism of actions, antidepressants act on these interconnected systems to increase CREB or BDNF, thus they have a similar effect on the final biological pathway. However, since antidepressants act on different receptors, the time to response and the symptom profile they act on at the beginning of the therapy may differ. Thus it would be rational to consider the symptom profile and desired time to response when choosing among antidepressants with different mechanism of action or switching from one antidepressant to another.