Activation syndrome is a form of sometimes suicidal or homicidal stimulation or agitation that can occur in response to some psychoactive drugs.[1] A study of paroxetine found that 21 out of 93 (23 percent) of youth taking Paxil reported manic-like symptoms which included hostility, emotional lability and nervousness.[2] Pfizer has denied that sertraline can cause such effects.[3][4] Approximately 25 to 40 perecent of patients who take tricyclic antidepressants experience activation syndrome upon initial titration.[5]