Nix all OTC "remedies"- they tend to be ineffectual, have side effects, and by suppressing the body's natural defenses (fever and mucus) actually worsen the underlying cause!
Something that I have found which actually treats the CAUSE is a product called Zicam nasal gel. (No connection to the company) It is not a decongestant, but purportedly the zinc keeps the viruses from reproducing in the nasal mucosa, from whence they spread about the body. By using it according to directions at the first onset of symptoms, oncoming colds have been headed off entirely!
One other thing: Antibiotics kill bacteria, not viruses. Those of you who take antibiotics at the first cold symptoms, KNOCK IT OFF! You're helping create resistant bacteria, without helping your cold.
Get well soon,
-Automan