I had cough syrup with prometh/codeine and I tried acetaminophen with it and I had some wierd seizures but I heard it's commonly used to enhance the painkilling
Just to clarify, acetaminophen (paracetamol, APAP) is a painkiller, codeine is an opoid painkiller, and cetirizine is an antihistamine. If you take them at the recommended doses, it should be fine....