It is a serotonin nor epinephrine reuptake inhibitor (SNRI) which is used in major depressive disorder,
generalized anxiety disorder, diabetic neuropathic pain, and stress urinary incontinence.
The most common side effects include fatigue, increased sweating, night mares, palpitations, blurred vision, postural hypotension ( sudden fall in blood pressure when standing from a sitting posture).
http://en.wikipedia.org/wiki/Duloxetine
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