What is the side effects of giving formula food to 2month baby?

Did not Understand!: There is nothing like formula food; mothers milk or one of the commercial infant formulas alone is given up to 4-6 months age(nothing else). After that supplementary food is introduced, e.g. Cereals, jar or home made pureed food. Breast feeding or infant formula is continued up to 1 year age. After that, 4% or vitamin-d milk up to 2 year, the 1%. Some follow up formula can be given instead at 1 yr.