Are there side effects to using lactose-free formula?

Yes, but all can : Babies do sometimes develop a diminished ability to digest lactose well for a week or two when they have a viral infection in the small intestines. Some pediatricians recommend switching to a lactose-free formula during this period. Nevertheless, when a baby doesn't seem to be tolerating a formula well, switching to another will sometimes do the trick. Different formulas affect stool consistency.