@ellemccope welcome to Mayo Clinic Connect. As you can see from other members’ responses Mirtazapine can be prescribed in different doses for various reasons. If you don’t mind sharing, why has it been prescribed for you? What kind of provider prescribed it for you and will s/he be monitoring & following it up? Could you tell this provider about the jitteriness? All meds have side effects. Maybe this is one of those and will require some fine tuning with your provider.