Have been on mirtazapine for 4years.can this have any lasting damage.

Mirtazapine: Also known as remeron, (mirtazapine) is an antidepressant that has relatively good safety and effectiveness profile. Long term issues tend to be related to potential side effects like weight gain or rare cases of agranulocytosis that tend to resolve after stopping the medication. Common issues include sedation. Many have taken it for years with good toleration.