Thats very strange because i read a article on risperidone and SSRI medication being a cause of serotonin syndrome. I dont know how well founded the research was however it was posted on rxlist.com awhile ago. I checked it recently and it dosnt mention anything about it now. Maybe this animal test is only recent and since the medication has been found not to cause serotonin syndrome when used with a SSRI im not sure. rxlist.com is normally a fairly good resource however it only states what the manufacturer of the drug has released.