Hello. I was prescribed Promethazine DM, for cough. I want to make sure this is not going to have a negative drug interation with blood pressure meds and most important, Tacrolimis (prograf) for liver transplant. I ve also had open heart surgery to get new tricuspid valve (damaged by radiation after lumpectomy.) Pacemaker lead tangled or melded with valve. This recent cold, one of VERY FEW - new insurance, new PCP. Prescribed Loratadine 10mg, can t tolerate, makes me sick. So is Promethazine DM going to make Tacrolimis inactive or change it significantly? I seem to tolerate the cough meds very well.