Should I Switch My Baby's Formula?

AngelaRD, LDN, CBS

Read time: 5 minutes

What should I know about switching my baby’s formula?

  • Understand that gas and spitting up can be a normal part of infancy

  • Know the symptoms of baby not tolerating their formula

  • Learn how to switch formulas if necessary

If your formula-fed baby is constipated, throwing up frequently, or gassy, you might wonder whether it’s time to switch baby formulas.

Occasionally babies will need a different formula, but there are also many instances where baby’s symptoms are quite common, and switching is not necessary. In fact, frequently switching formulas can potentially upset your little one’s belly even more!

If you are unsure about whether switching baby’s formula is the right choice for you, chat now with one of our Happy Experts for free.

Learning Center - More info on formula

What symptoms are common during infancy?

Spitting up

While uncomfortable for us to watch, spitting up is quite normal in newborns.

While each baby is different, this symptom is mostly due to an immature digestive system. The sphincter between baby’s stomach and esophagus is still a little weak, compounded with how much time baby spends on their back and it’s no wonder milk can come back up so easily.1

Infrequent bowel movements

You may be wondering if you should switch formulas due to a constipated baby. Most formula-fed babies pass stools at least once daily; however, some may go one to two days between bowel movements.2

Newborns and young babies have to work very hard to pass stools since their abdominal muscles are still weak, so even if baby is fussing, grunting, straining a bit and turning red while trying to pass stool, it’s normally not an immediate cause for concern.

Read more: How Can I Relieve Constipation for My Baby and Toddler?


Gas is also an often unavoidable symptom and usually happens when baby swallows too much air while crying or drinking from the bottle.3

Gas bubbles can be painful for baby, but as your little one’s digestive track and abdominal muscles get stronger, they’ll be better at handling this symptom.

Sometimes encouraging a full baby to finish their bottle can cause baby to be gassy or to spit up quite a bit. To help prevent this, follow baby’s hunger and fullness cues, stopping when your little one indicates they’re done.

Read more:  Understanding Your Baby's Hunger and Fullness Cues: Responsive Feeding

How can I help my baby with gas and passing stool?

Gently pulling and pushing baby’s legs in and out, bicycling baby’s legs, and light belly massage can all help get things moving.4 

Always speak with baby’s doctor if the constipation isn’t getting better, if stools are bloody, or if you have any other concerns.

Spit up and gassiness continue to be normal even as your baby ages. Once solid foods are introduced, you will see further changes in baby’s bowel habits. Stools become a bit less frequent, smellier, may change color, and become firmer.5

Read more: How Do I Relieve Gas In My Formula or Bottle-fed Baby?

Signs your baby may not be tolerating their formula:

  • Eczema

  • Typical allergy symptoms such as wheezing, hives, excessive vomiting.

  • Bloody diarrhea

  • Severe constipation

  • Excessive fussiness after eating

  • Forceful vomiting

  • Failure to thrive (baby is not gaining weight at the expected rate)6

Most of the time, allergy or intolerance issues are due to the milk or soy proteins present in cow’s milk and soy-based formulas, although other ingredients could be the culprit. It’s rare for a baby to be lactose intolerant.7

When to switch infant formulas

It’s always important to consult with baby’s pediatrician when you feel that you need to switch baby’s formula.

If a milk allergy or significant intolerance is suspected, soy formula is often bypassed for a partially hydrolyzed formula or occasionally a different form (concentrate versus powder versus ready-to-feed) or brand.8

But it is important to speak with baby's pediatrician before making any decisions. 

How do I switch baby formulas?

Here are tips on transitioning to a new formula if baby's pediatrician recommends the switch.

When transitioning your baby from one formula to another due to an allergy, intolerance, or medical condition, an immediate switch is usually recommended (as opposed to a slow transition). Confirm the appropriate formula transition timing and switch with your baby’s pediatrician.

In the absence of an allergy, intolerance or medical condition that would warrant switching formulas immediately, some parents choose to transition between formulas slowly.

If you decide on the slower course, use the guide below and transition to the next step every 1-2 days. Assuming baby takes 4 oz of formula:

  • 3 oz current formula, 1 oz new formula

  • 2 oz current formula, 2 oz new formula

  • 1 oz current formula, 3 oz new formula

  • 4 oz new formula

Know what’s normal and wait for results

In the end, it’s important to recognize what’s normal and what’s a red flag regarding baby’s digestion.

Before considering a formula switch, double-check to make sure you are preparing the formula properly and that you are following baby’s hunger and fullness cues.

It’s also important to know that changes won’t happen overnight after switching your baby’s formula. It could take a week or two for a baby to get used to a new formula and for their symptoms to go away completely.

Let’s Chat!

We know parenting often means sleepless nights, stressful days, and countless questions and confusion, and we want to support you in your feeding journey and beyond.

Our Happy Experts are a team of lactation consultants and registered dietitian nutritionists certified in infant and maternal nutrition – and they’re all moms, too! They’re here to offer personalized support on our free, one-on-one, live chat platform Monday through Friday, from 8am–6pm (ET). No appointment needed, no email or sign-up required. Chat Now!

Read more about the experts that help write our content!

For more on this topic, check out the following articles:

Does your Baby Need a Sensitive Formula?

Formula Feeding On Demand Vs. on a Schedule

How can I Manage my Baby's Colic?

How Much Formula Does My Baby Need?