Background:

Guaifenesin is an expectorant that also has some muscle relaxing action.Target: OthersGuaifenesin is thought to act as an expectorant by increasing the volume and reducing the viscosity of secretions in the trachea and bronchi. It also stimulates the flow of respiratory tract secretions, allowing ciliary movement to carry the loosened secretions upward toward the pharynx. Thus, it may increase the efficiency of the cough reflex and facilitate removal of the secretions; however, objective evidence for this is limited and conflicting [1].

参考文献:
[1]. Bennett, S., N. Hoffman, and M. Monga, Ephedrine- and guaifenesin-induced nephrolithiasis. J Altern Complement Med, 2004. 10(6): p. 967-9.