why do all these people seem to think that Guaifenesin is the bronchodilator, I'm very cusious where this info is coming from. "thin the mucus and clear airways" that is the bronchodilator doing that which is the ephedrine. All Guaifenesin is is a muscle relaxant like omega said. why a body builder would want to take a muscle relaxant I have no idea, buy the pure stuff forget that Guaifenesin crap.