My doctor says it is o.k. to take Vitamin C along with the COPD medication that he has prescribed for me; such as a nebulizer (albuterol along with some other med, prednisone (temporary for 10 days) and Trelegy (which is supposed to work good; but haven't found too much difference so far), I am taking all these and now if I want to take some of the NAC (from vitamin store) would I have to ask the doctor if it is o.k. to take? I don't know. I think it would be o.k. to try (people say it works great; so I would like to try it). Any help with this question, sure would be appreciated.