Ketamine, a molecule mainly used as an analgesic in palliative care, turns out to be an excellent fast acting antidepressant. By acting as an NMDA receptor antagonist, its mechanism of action is complementary to classical and long acting antidepressants like Selective Serotonin Reuptake Inhibitors (SSRI). In particular, ketamine is able to boost synaptogenesis in only a few hours whereas long-term prescription of SSRI can stimulate neurogenesis.