Dextromethorphan
"It's been years  since I've taken any robitussin. I should have stayed with just the Tussin  



This was Robitussin DM nighttime , but has the same active ingredient of detromethorpiphan.  I did not have much in my stomach so that may have been the problem.  But it's been 24 hours and I still have diarrhea, but it was worst while sleeping ando waking up after it was too late....FOUR times. That has never happened to me in my life.   The cough syrup was the only new thing. I've been dehydrated all day, drinking Pedia late and rice and bananas.  At least I'm making it to the bathroom.  Never again! Ugh!  Remember, your small intestines are 22 ft long, so it could take 2 days to get out of you system!    Not ever taking the chance again"