Duloxetine (Cymbalta, and generics) is a serotonin-norepinephrine reuptake inhibitor (SNRI) created by Eli Lilly.It is mostly prescribed for major depressive disorder, generalized anxiety disorder, fibromyalgia and neuropathic pain.uloxetine was approved for the treatment of major depression in 2004. While duloxetine has demonstrated improvement in depression-related symptoms compared to placebo, comparisons of duloxetine to other antidepressant medications have been less successful.