Suggest Treatment For Cold And Dry Cough In Children

hi doctor, my kid has 3 years old.he was suffering from bad cold & dry cough from the last month.doctor prescribed s-mucolite and nebulizer.in that i used duoline mixing with NS water.it was redused.but again it came.i used the nebulizer again.but now i did not use any medicine just i used NS water.is there any benifit for just using NS.