Mixed feeding making my 5mo sick?

[Mull]

Hi

I'm starting to switch my 5mo DS from BF to FF as I start back at work soon and don't want to do expressing at work or the 'reverse cycle' thing.

He's always taken a bottle well (been giving a EBM bottle once a day from about 8 weeks) but I don't think the formula is agreeing with him. He's always been sick a lot but he seems even worse with formula. Ive tried normal Aptamil, Aptamil Comfort and started using the C&G cartons yesterday (heard they were more sterile than the powders?).

Is it likely that the mix of breast milk and formula is not agreeing with him? Should I make the switch more quickly than I planned? I really don't want to stop using the formula but I'm sure he's bringing back whole feeds over a couple of hours.
Any suggestions / experiences?

It could be reflux (you say he's sick a lot) and/or a cows milk intolerance.

My DS has reflux and intolerant to cows milk protein. I BF and gave up dairy as it would affect him otherwise. At 6 months I tried him with a little bit of formula as I had heard some babies grow out of it then. He hadn't and would be worse after having a few ounces of formula, throwing up a lot and very windy. Now at 11 months, if I give him a spoonful of yoghurt he's sick (as I check every few weeks to see if he's grown out of it).

It's unlikely that the mix is bothering him - more likely the formula is.

What you can do is speak to your GP to get a prescription for hydrolysed formula and gradually wean your baby onto that (by mixing formula and BM, then increasing the formula to BM ratio). The cows milk protein is broken down so intolerant babies can drink it without being sick. It tastes quite rank but babies get used to it.

You could continue to BF in the morning and evenings plus a dreamfeed and use the hydrolysed formula for the day.