Aided by the launch of Rx-to-OTC switch brand Allegra (Sanofi-Aventis) and strong growth of private labels, allergy relief products grew 16.3% in 2011 to become the fastest growing category on the U.S. OTC drug market, according to the Nonprescription Drugs USA 2011 report by international consulting and research firm Kline & Company. The U.S. OTC drug market posted a gain of 2.4% reaching $21.4 billion in 2011 at the manufacturers’ level. Past Rx-to-OTC switch brands continued to perfor...