Hi Dear , As per your query you have facial numbness along with blurred vision while on Mirtazapine . There can be many reasons for the symptoms you mention in query , But in your case it seems to me that there are two things that are responsible that is :- - First the facial numbness is probably due to bell s palsy . Bell s palsy is a condition that causes temporary weakness or paralysis of the muscles in one side of the face. - Secondly the numbness of extremities is probably due to ulnar nerve dysfunction . There can be other reasons also like side effects of certain medicine and allergic reaction. I would suggest you to consult neurologist for proper diagnosis and rule out condition like diabetic neuropathy and trigeminal neuroptahy . Doctor may conduct various test to confirm the diagnosis . Doctor may prescribe myscle relaxant or anti inflammatory . Doctor may also recommend physical therapy , massage or light muscle exercise . Sometimes doctor may give alcohol injection in nerve base . Hope your concern has been resolved. Get Well Soon. Best Wishes, Dr. Harry Maheshwari