Here’s How to Switch Your Baby’s Formula if You Need To

If you're struggling to find your baby's go-to formula or want to switch, these expert-approved tips will help you do it safely and effectively.

Medically reviewed by Natalie D. Muth, M.D.

Whether it's because of an intolerance, allergy, medical condition, or even the baby formula shortage, parents may need to switch to a new baby formula. But it's normal to have tons of questions about how to switch baby formula and when to do it.

The main question is likely whether or not it's safe. The good news is experts says it is OK to swap to another brand. The best thing to do is to try to buy a generic store brand that's similar to your current formula and watch your baby for any side effects.

Also, don't make baby homemade formula or dilute formula. And don't give your baby cow's milk before age 1. Babies can't digest cow's milk as easily and it also doesn't have enough nutrients before age 1, according to the American Academy of Pediatrics (AAP).

Pediatricians weigh in more about the best practices for changing formula brands, along with possible side effects and other considerations.

Can You Just Switch Baby Formula?

Switching to a different formula brand is perfectly fine.

"There is no danger in providing your baby with differing formulas from one day to the next, especially if they have the same base," says Wendy Sue Swanson, MD, MBE, FAAP, pediatrician and chief medical officer of SpoonfulONE. She makes the comparison that breastfed babies also have differing milk each day due to changes in the parent's diet, creating a "slightly different recipe at every feed."

Plus, the nutritional composition of different infant formulas is similar. "While the source of components may vary, the proportions and amounts of nutrients that your baby gets are the same among different brands," says Rashmi Jain, MD, a concierge pediatrician in Irvine, California and founder of BabiesMD.

It's also generally fine for most babies to switch between ready-to-feed, concentrated liquid, or powdered formula. "The exception might be preemies or immunocompromised babies under 3 months of age who may not be able to take powdered formula yet," says Dr. Jain.

Dr. Jain stresses you shouldn't transition a baby who's on speciality or hypoallergenic formula (like Similac Alimentum or Enfamil Nutramigen) to sensitive or standard formula without a pediatrician's approval. You can technically give hypoallergenic formula to an infant who's been using the standard cow's milk-based formula, but this isn't recommended; parents should save speciality formulas for those who need them.

Which Type of Formula Should You Choose?

Are you struggling to find the formula your baby was previously on? "Switch to a generic/store brand formula that is equivalent to what your baby was on before," says Erika Cantu, MD, a pediatrician practicing in Houston. "This is really safe to do and is essentially the same formula."

Don't worry if you can't find the generic or store brand version though. All formulas sold in the United States are regulated by the Food and Drug Administration (FDA). They also contain the proper mix of nutrients for babies, says Bridget Young, PhD, a certified lactation counselor and an assistant professor of pediatrics at the University of Rochester. If you're unsure which formula to choose, talk to your child's health care provider; they might have recommendations or samples to try.

That said, babies with food allergies or digestive issues have additional needs, and they might need to stay on certain speciality formulas. "Parents of infants on very specialized formulas like those amino-based or extensively hydrolyzed formulas should reach out to their physician before making the change," says Dr. Cantu.

How to Safely Switch Baby Formula

Ideally, if you're changing your baby's formula, you should do it gradually to check for any intolerance or sensitivity to a new brand.

If you still have some of your baby's old formula on hand, Dr. Swanson advises the following:

• Gradually make the switch by mixing three parts old formula and one part new formula

• If the baby drinks it, move to half and half

• Then move to 1/4 old and 3/4 new

• Following that would be a full bottle of the new brand

"If possible, try to make this transition over the course of one or two weeks," says Dr. Swanson. Use the scoop provided with the formula because scoop sizes may vary between brands.

But the most important thing is making sure your baby is fed. So, if you have to switch formulas quickly, Dr. Swanson offers words of comfort for any anxious parents in this situation. "Some families may have to make the switch to a new formula cold turkey and that's OK and typically well-tolerated in babies," she says. "Don't let switching from one formula to another add to the stress you already feel. Your baby will do well."

Side Effects of Switching Formula Brands

Although it's safe to change your baby's formula brand for a variety of reasons, you may notice some changes in your infant. Dr. Swanson says babies may:

• Get constipated

• Poop more frequently

• Have their poop's consistency change

• Be gassy

Babies may also react to the new taste by turning their head away or refusing the bottle. All these side effects are temporary and may last a few days. But experts point out there isn't much difference between baby formulas so most babies generally don't have a problem switching between them. Also, the formula may not be the reason why a baby seems fussy so always reach out to a health care provider if you notice any changes.

Signs of an Intolerance to a Formula

You should pay attention to any signs your baby is not tolerating a formula. This means your baby isn't digesting the formula properly. Signs can include:

• Diarrhea

• Vomiting

• Blood or mucus in stool

• Signs of pain, including pulling legs up toward the abdomen while crying

• Constant crying

• Losing weight or trouble gaining weight

Call your child's health care provider for any signs of intolerance. A change of formula is likely needed and the health care provider may need to examine and treat your baby for any lingering issues.

And stop using a formula immediately and call your child's health care provider if you notice any dangerous red flags, such as trouble breathing or bloody stool.

How Long Does It Take for a Baby To Adjust to New Formula?

Babies may need a little time adjusting to a new formula. "It can take a week or so for a baby to adjust to the change," says Dr. Swanson.

According to Dr. Young, parents can wait 10 days before deciding whether a new formula is not working.

Again, make sure to pay attention to any intolerances to a new formula and speak with health care provider if you need to.

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