Amitriptyline, sold under the brand name Elavil among others, is a medicine used to treat a number of mental illnesses. This includes major depressive disorder and anxiety disorder, and less commonly attention deficit hyperactivity disorder and bipolar disorder. Other uses include prevention of migraines, treatment of neuropathic pain such as fibromyalgia and postherpetic neuralgia, and less commonly insomnia. It is taken by mouth.