Serotonin syndrome is a potential adverse reaction to drugs increasing serotoninergic activity in the nervous system, some of them being frequently prescribed, such as antidepressant drugs. As clinical presentation is variable and often aspecific, diagnosing serotonin syndrome can be a challenge, particularly in mild cases. Serious forms can be lethal. The aim of this article is to increase practitioners awareness of this syndrome by reviewing current knowledge on physiopathology, clinical presentation and therapy. We also analyzed the 102 cases notified to Swissmedic from 1998 to 2009, focusing on patients profile and suspected drugs.