I have never heard anything about methotexate changing the blood alcohol level. The concern with this drug, as you know, is potential liver damage. I'm not sure I know what you mean by "some adverse affects due to the low blood count." However, blood cell count and platelet count have nothing to do with alcohol blood level, as far as I know. However, I am not expert on breath and blood testing for alcohol, so I can't comment on that particular question with any expertise.
Best.
Dr. Rockoff