shouldn't affect you. it'll be like 24 hours later right?? are you sure Nyquil has DXM in it anyway?? I thought only Robitussin DM had it.
look at the ingredients on the side of the bottle and see if it has dextromethorphan in it. if it does, then that's DXM.
but anyhow, you'd have to drink like the whole bottle to get a harmful amount in your system, so like I said you'll be fine.
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"Stay positive and love your life."
-Nicholas Lofton Hexum