Serotonin norepinephrine inhibitors (SNRIs) are a class of antidepressant medications that work by increasing levels of serotonin and norepinephrine in the brain. SNRIs are used primarily to treat major depressive disorder and other conditions such as anxiety disorders, menopause-related symptoms, fibromyalgia, and chronic muscle or bone pain. Some common SNRIs include duloxetine (Cymbalta),...