Cymbalta^® (duloxetine hydrochloride) is approved to treat symptoms of depression, neuropathic pain, fibromyalgia, and generalized anxiety disorder. Because this prescription medication is a serotonin-norepinephrine reuptake inhibitor (SNRI), it may affect several chemicals in the brain, including serotonin and norepinephrine. It is possible to take too much Cymbalta. Make sure to seek immediate medical attention if you think you may have overdosed on Cymbalta. Signs of an overdose can include vomiting, hallucinations, and seizures.