Amitriptyline is a popular antidepressant that's available only in generic form in the U.S. It used to be sold under the brand name Elavil. Amitriptyline is classified as a tricyclic antidepressant. For years, some doctors have considered it a front-line treatment for fibromyalgia and chronic fatigue syndrome (ME/CFS). However, this came about more from trial-and-error use than clinical studies.