When switching to a new formula, a baby's digestive system might take some time to adjust. The baby may experience gas, bloating, constipation, or diarrhea. This is usually temporary and should resolve within a week or two.

A change in formula can lead to changes in the color, consistency, and frequency of a baby's stools. For example, stools might become darker, lighter, more solid, or more frequent.

Different formulas may have variations in taste and texture. The baby might initially reject the new formula due to these differences, but they usually adapt to the change within a few days.

Although rare, some babies might have an allergic reaction to the ingredients in the new formula. Signs of an allergic reaction include rash, hives, swelling, difficulty breathing, or excessive fussiness. If any of these symptoms occur, contact the pediatrician immediately.

When switching formulas, the baby might consume more or less formula than before. This could be due to differences in taste or the baby's digestive system adjusting to the new formula. Monitor the baby's intake and weight gain to ensure they are getting enough nutrients.