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

Hello, I can understand how difficult it becomes at times to feed the baby medicine but this option of mixing medicine with food is available to parents all the time and doctor too knows the fact that children throw tantrums in having medicine even then they do not tell you that feed the baby medicine mixed with food. I think there must be some valid reason behind this. Doctors say that certain foods have certain chemicals that can interfere with the body system. https://www.fda.gov/downloads/Drugs/.../GeneralUseofMedicine/UCM229033.pdf%20%5Baccessed%2024July%202013