my 90 year old mother takes zantac and coreg. She is reading that this could cause side effects. She has stage 2 lung cancer, a rather large tumor 4+cm. She has gone through chemo(did not help) and 10 radiation treatments. She coughs up mucous daily. Also takes mucinex for that. She has been on the rantadine for a couple of years for acid reflux. Are the combo of these drugs causing the mucous or is it mainly the tumor in your opinion? thank you