Black cohosh for low thyroid levels?

got my ths tested it was 1.0 my t3 and t4 are ok so i was not perscrobed synthroid. however i am still dealing with the symptoms. doctor said my charts indicated ive alaways had low levels. anyways i was told by a pharmacist to take black cohosh sipplement. i orginally went in for iodine supplement but he advised against it saying it will kill my thyroid? any expeirance with this black cohosh.