Guaifenesin possesses mucolytic properties. Mucolytics are agents that alter the structure of mucus to decrease its viscosity and therefore facilitate its removal by ciliary action or expectoration. Although mucolytic  have  been  shown  to  affect  sputum  viscosity  and  structure,  and  patients  have  reported alleviation of their symptoms, no  consistent improvement has been demonstrated  in  lung  function. guaifenesin is reported to reduce the viscosity of tenacious sputum and is used an expectorant. On the other hand, Salbutamol is a direct acting sympathomimetic agent with predominantly beta-adrenergic activity and selective action on beta2 receptors. It is used as a bronchodilator. It has more prolonged actions than isoprenaline and as a  predominantly beta2 stimulant, has a bronchodilating  action relatively more prominent than its effect on the heart. An additional beneficial effect of Salbutamol is its action on the uterus as a relaxant, the uterine muscles as we all know contract under beta adrenergic stimulation. Thus  it  has  gained  popularity  among  obstetricians  for  controlling  premature  labor however,  a  relative  contraindication  to  its  used  is  among  pregnant  patients  with  vaginal  bleeding because it may cause pulmonary edema on them.