CHICAGO - DECEMBER 05:  Robitussin cold medicine containing dextromethorphan is offered for sale at a retail store December 05, 2006 in Chicago, Illinois. According to reports, between 1999 and 2004 the abuse of over the counter cough medicines, many containing dextromethorphan, has risen 50% a year, mostly among youths. Getty Images logo Getty Images 36 months ago

CHICAGO - DECEMBER 05: Robitussin cold medicine containing dextromethorphan is offered for sale at a retail store December 05, 2006 in Chicago, Illinois. According to reports, between 1999 and 2004 the abuse of over the counter cough medicines, many containing dextromethorphan, has risen 50% a year, mostly among youths.