Can fluoxetine or concerta be fatal at a certain dose?

Interaction: There can be serious interaction when fluoxetine and Concerta are taken there have been reported cases of serotonin syndrome, which a serious matter and has been related to deaths in the past. Other interactions include increased anxiety, depression, asthenia, fatigue, suicidal ideation, nausea, pain, constipation and dizziness. Speak to your prescriber about monitoring for problems.