The treatment of cough in children depends on the underlying cause.The oral antibiotics like amoxycillin, septran may be given to control the bacterial infection which may be a cause of coughing.
The other causes like bronchial asthma or allergy should also be ruled out.The treatment is according to the underlying cause.
The OTC cough medicines should be avoided in childern as it may cause drowsiness.Though you may give her honey which has found to be beneficial in coughing.
If the cough still does n't stop then consult the doctor and have the relevant test done like blood counts, chest ausculation, x-ray chest to know the associated abnormality.
Please see the link for more info
1) causes of cough in children
Please feel free to ask me any doubt.