My 7 months child she is been coughing about a week and half i took her to a doctor got prospan medicine but no different, she not coughing constantly but when she cough it's scares me?

Basics: Coughing is a natural protective event that helps clear the lower airways of small amounts of mucous. The point of onset is often a minor upper/lower airway virus of little importance (self healing). Recovery/clearing is often delayed by exposure to environmental irritants like house dust, fragrances,smoke,etc. Even relatively minor lower respiratory viruses can lead to cough for a month.