Is it okay to mix the medicine with the milk? E.g syrup for cough.

No. My brother is a pharmacist and sabi nya ang pag inom ng gamot ay dapat tubig lang and hindi pwedeng ibang liquid, dahil maaring hindi tumalab ito sa ating katawan.

I believe it's ok kasi my parents were doing that to us when we were young. Pag ayaw talaga namin inumin yung medicine, they had to mix it sa milk.