The “hydration hypothesis” proposes that guaifenesin, by increasing the effective hydration of the respiratory tract, maintains the sol layer needed for ciliary clearance and reduces the viscosity of respiratory mucus, thereby further facilitating its removal by natural clearance processes.Perhaps the findings of the present study
may be explained by increased mucus volume, or otherwise altered airway mucus, serving as a more
effective barrier shielding cough receptors within the respiratory epithelium from the tussive stimulus.