Anyone's lo coughing heavier after taking cough med? She's 4 mths now

I have consulted my baby's pediatrician about the same concern just last Sunday. I told her that I noticed my baby's cough got worse after taking medicine. She said it's really the purpose of any Mucolytic is to loosen the phlegm that's why after drinking it, it triggers the baby to cough more. It only means that the mucolytic is taking effect. Give it 3-5 days and the cough should be removed by then.