Cymbalta^® (duloxetine hydrochloride) is a prescription medication that is approved to treat fibromyalgia, depression, peripheral diabetic neuropathy pain, and generalized anxiety disorder. The medication works by increasing the levels of certain chemicals of the brain (serotonin and norepinephrine) and possibly by blocking the nerve pain signals in the spinal cord or brain. Possible side effects of the medication include nausea, insomnia, and dizziness. If the side effects become too bothersome or if the medication does not work as well as intended, there are other alternatives to Cymbalta, including other medications and therapy.