Guaifenesin is an expectorant which decreases the stickiness of mucus (phlegm) and helps in its removal from the airways. Terbutaline is a bronchodilator. It works by relaxing the muscles in the airways and widens the airways. Bromhexine is a mucolytic which thins and loosens mucus (phlegm), making it easier to cough out. Together, they make breathing easier