Yes, zinc. In my experience over maybe 5 years, if I start taking zinc tablets immediately the first day that I feel a cold coming on, it goes away. If I don't take the zinc, and get the cold, zinc seems to speed up the recovery, but doesn't "cure" it. I start with 2 tablets first dose, then 1 tablet 4 times a day. I currently have 50mg zinc tablets. I take them with me when I travel.
But I've noticed that when I do get a cold, it's a mother... perhaps by not having as many colds, my resistance is lower?
Oh, and I sip Jim Beam neat and take tylenol instead of taking cough medications.