Part of a class of drugs known as tricyclic antidepressants, Elavil^® (amitriptyline hydrochloride) is used for treating depression. While it is not entirely clear how Elavil works, it is known that the drug affects several chemicals in the brain, including serotonin and norepinephrine. Some "off-label" uses for Elavil include helping with ADHD, fibromyalgia, bedwetting, and bulimia. Common Elavil side effects may include difficulty urinating, constipation, and confusion. Elavil comes in a tablet form that is usually taken by mouth one to three times a day. If you do not take your Elavil dosage as scheduled, take your next dose as soon as you remember. But do not take a double dose. Among the conditions you should let your healthcare provider know about before taking Elavil are hyperthyroidism (overactive thyroid), severe anxiety or agitation, difficulty passing urine, and bipolar disorder or a family history of bipolar disorder.