I've tried it. Normally, I don't go in for that sort of thing. I think of them as placebos, mostly. But, I've had this cold that has hung on for a very long time. I figured, "what the hell". Nothing wrong with a placebo every once in awhile. I picked up the Cold FX three day package (Day 1 = 3 pills 3 times a day, Day 2 = 2 pills 3 times a day, Day 3 = 1 pill three times a day). I felt a bit better, but ... better than I would have felt? Can't say.
So, felt a little better, but I still had this terrible cough. I got plenty of rest, I always eat well, I take multi-vitamins. Finally, after 3 or four weeks, I read an article in the newspaper that said that most persistent coughs were caused by nasal drip in the back of the throat. It suggested using a saline nasal spray. Made sense. So, instead of paying $2 for less than a tablespoon of salt water, I made my own (1/4 tsp of salt, 1 cup warm water). I did that and gargled with salt water once a day. Presto, the cough went away almost immediately. I was floored at how fast I felt better. Home remedies ... go figure.
So, Cold FX = maybe it helped. Can't say.
Gargling with salt water and using a saline nasal spray = miracle cure.
Cold FX (which contains zinc and ginseng) brags about the clinical trials they passed, but really there was only 1. That I could find, anyway. It was done with a small group (about 200) and the scientists were associated with the manufacturer. This does not automatically mean the trial isn't trustworthy, but it isn't really glowing proof that it works. Here's a link:
http://www.ncbi.nlm.nih.gov/entrez/q..._uids=14687309
Here's a link on nasal sprays. That last little bit is about the saline sprays:
http://allergies.about.com/cs/sprays/a/aa113098.htm
So, that's what I know.