I am not sure about giving both together, but I wanted to say that if you still think your baby has reflux and the mylanta is not working well, go back to the GP and ask to try something else. My DS had reflux and he was started on Mylanta which made a difference for the first couple of days and then it kinda wore off. I went back to the GP and he went on to Zantac, which once again made some difference but not heaps, eventually he was put onto Losec and he was like a new baby.

I also thought my DS had colic and not reflux, but once his reflux was under control his 'colic' symptoms disapeared.