Ask BK:
I'm late in answering the recent TOD about cold remedies, and I don't remember if you said you ever try cough medicines, specifically.
My go-to is Robitussin DM (don't ask me what the variations mean, I just know the "DM" variety works for me), and I do fine with cheaper store brand equivalents, usually called Tussin DM or some such.
Lately I've learned my lesson, which is to start taking it while I have the cold and NOT wait till the cold's almost passed and I'm starting the ubiquitous lingering cough. However, that being said, it's never too late to start. When I was first introduced to it, I was in the throes of constant coughing following a cold, and it absolutely helped to quiet it and give me some peace and relief. Highly recommended by me, regardless of whatever other cold remedies a person likes.