Mirtazapine (Remeron^®) is used to treat the symptoms of depression, which can be caused when certain chemicals of the brain become unbalanced. Although it is not entirely clear how the drug works, it is believed to help keep levels of norepinephrine and serotonin balanced. The medication comes in tablet form and as an orally disintegrating tablet that is taken once a day. Because mirtazapine can interact with other medications, it is important to tell your healthcare provider about all of the medicines you take, including prescription and non-prescription medicines, vitamins, and herbal supplements.