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 urine 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.