I saw this article and this explains more about why the FDA is recommending cold meds not be given to children under 6. There is statistical evidence. More than 7,000 children are rushed to the ER every year after suffering adverse reactions to cold medications. In 2004 and 2005 more than 1500 children suffered from complications and 123 died after taking cold medicines. There are also a variety of factors: parents giving the wrong medicine or the wrong dose, and in some cases children themselves found their way into the bottles.
Here is a link to the entire article: http://www.washingtonpost.com/wp-dyn/content/article/2008/01/28/AR2008012801938.html