It doesn't for me unless I've taken too much expectorant...but that would be softer stool, not diarrhea.
But, there are so many different viruses..if one really ups the immune system,it could cause everything else to rev up as well, including the digestive tract.
If it seems to get worse, I would suggest upping rectals.
Hope you feel better soon. I had something like that a year ago..ugh! I was sick for 2 weeks.
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