Amitriptyline hydrochloride (Elavil^®) is a prescription drug licensed for the treatment of depression. The medicine is part of a class of drugs called tricyclic antidepressants. While it is not entirely clear how amitriptyline works, it is known that the drug affects several chemicals in the brain, including serotonin and norepinephrine. Amitriptyline comes in a tablet form that is usually taken by mouth one to three times daily. It should be taken at the same time each day to maintain even levels of the drug in your blood. Amitriptyline tablets are available in the following six strengths: 10 mg, 25 mg, 50 mg, 75 mg, 100 mg, and 150 mg. Side effects of amitriptyline can include confusion, a dry mouth, drowsiness, and constipation.