Why do some of your doctors say it’s ok to take tramadol and fluoxetine together - and some don’t?

Serotonin syndrome. Tramadol has SNRI properties, so it is serotonergic. When combined with other serotonergic meds like fluoxetine, there is potential for serotonin syndrome. Depends on the doses, really, and the individual's tolerance to serotonergic agents. Some docs are more comfortable than other co-prescribing serotonergic drugs. I've safely co-prescribed these, but I've always been vigilant about monitoring.