What is normal when switching formulas?

Lacey

I’m switching my twins from Similac Sensitive to Similac Total Comfort. In the same day we started them on reflux medicine. They both have been spitting up a lot of their bottles since we gave them their first dose of the med last night. Is it normal to spit up that much when switching to diff formulas or do you think it’s the med upsetting their tummy?