When you're shopping for infant formula, you might wonder if it's prudent to switch brands if another brand is on sale. If your baby is doing well on one formula, you might worry that changing brands could cause side effects, such as diarrhea. While stool characteristics might change, switching among formulas of the same type should not cause diarrhea. Changing between types of formula -- from hypoallergenic to milk based, for example -- could cause diarrhea if your baby has a milk allergy.
Formula brands might contain varying protein ratios and different fats. While these differences could cause your baby's stool to change color -- becoming green if the formula contains iron -- or harder or softer, these changes don't affect your baby's health. Some formulas, such as hydrolyzed protein formulas used for infants with milk allergy, cause more frequent stools. If your baby develops diarrhea -- defined as a sudden onset of more than 3 loose, watery stools in a 24-hour period -- let his pediatrician know, as diarrhea can cause dehydration.
How to Switch
You do not need to gradually switch from one formula to another to prevent side effects such as diarrhea. You can change your baby from one formula to another without mixing the two or alternating between the old and new formula, as long as you're using the same category of formula. Do not change formula types without your pediatrician's approval.