Cold medicines, sudafed, benadryl, even Tylenol PM are all things that have caused me to think about drinking/triggers. This is just my own personal opinions on why...but I think it's because all those things have things like Diphenhydramine in them. Diphenhydramine is something that relaxes you a bit and slows your thought process down a tab and makes you sleepy....sound familiar? So for me at least, when I take that it almost makes me feel a little bit like I have been drinking, and when I feel that way then my mind says "hey...why not go for it?".
Steve