"About 800 pediatric cough and cold products are sold in the United States that use one or more of 39 drugs. But every study performed in recent years shows that these medicines have no effect, and a growing number of reports have concluded that they can be dangerous. The American College of Chest Physicians recommends that these products not be used in children..."
That is an excerpt from an article in the New York Times describing a federal drug safety official's rationale for his request that children's cough and cold medicines be banned. Kudos to this guy. We know these drugs have no positive effect on the viruses that cause cough and cold, that some ingredients in them actually depress the immune system (like like Tylenol), and that these drugs basically exist to line the pockets of their makers at the expense of the users health.
The best things to ward off colds and cough in children are: loving and caring parents, excellent nutrition, lots of exercise and sunshine, and lastly, Andrographis Paniculata--the one herb that has been shown again and again to both prevent and decrease the severity of colds and flu. You can buy it right here or at my office in town.