Whole milk


I’m a FTM and our son is on formula. This past check up our doctor told us to start using whole milk at age 1 and I was just wondering if the switch will cause some tummy pain for my little one? Any mommas from past experience noticed their babies getting an upset stomach or anything when they switched to cows milk? Did your baby like it at first? Did you give the milk as regularly as you have formula/breast milk??

Thanks in advance :)