How to stop my daughter from coughing in middle of night?

I have a super active but adorable 4 year old daughter. She loves to run around & play actively. However, she will have a bad dry cough in middle of night (abt 4-5am) & I have to resort to giving cough syrup to alleviate her cough. Don't want her to get addicted to the cough syrups & would like to seek any alternative opinion from those that ever had the same problem with their kids. Do let me know as feeling exasperated...