Signs Formula Doesn't Agree with Baby: What to Look For

Signs Formula Doesn't Agree with Baby: What to Look For

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One of the most challenging aspects of having an infant is learning how to decipher what they need, especially when it comes to feeding issues. However, while your baby can’t tell you with words that something is wrong, they can offer other signs that you may need to make a change to their formula. 

How to Know Which Formula is Right for Your Baby

Not every infant formula is going to work well for your baby, and that’s okay. But how do you know which one is the right one? The most important factor to consider when changing formulas is to ensure it is adequate in its ability to support normal growth and development of your baby.

However, it’s also important that your baby tolerates the formula well and enjoys drinking it. Otherwise, he or she isn’t going to get the intended benefits of consuming it. Plus, you don’t want your baby to be uncomfortable or experience a negative reaction to drinking a certain type of formula. 

When choosing a baby formula to try, consider options like the main protein source, the ingredients, the preparation method, and whether the type of formula aligns with your family’s needs and preferences. 

For example, you may be trying to decide between a protein made with soy or cow’s milk, a traditional or hydrolyzed formula, or a ready-to-eat versus a powdered formula. For guidance on choosing a baby formula and examining what’s inside of all the options, see this post

If you ever have questions about what formula is best for your baby, it’s a good idea to speak with your child’s pediatrician or a registered dietitian who specializes in pediatrics for tailored advice.

Signs that Formula Isn’t Agreeing with Baby

Signs that Formula Isn’t Agreeing with Baby

Once you’ve chosen a baby formula, this is when somewhat of an experimental period begins. Some babies may tolerate formula for a while, and then eventually something changes and you notice that a change may need to be made. 

Before we get into signs that you may need to switch formulas, it’s also helpful to know how to tell if a formula is working well for your baby. 

For instance, signs that your baby is doing well on formula include having at least 5 wet diapers and at least 1-2 bowel movements per day, signs of normal growth at wellness visits, and an overall relaxed and satisfied demeanor after eating. 

On the other hand, there are also plenty of signs that your baby may need a formula change. Some of these include: 

1. Diarrhea

A baby’s poop is constantly changing, especially as its digestive system continues to develop and be exposed to new things. It’s also common for bowel movements to change when your baby gets sick or stressed. 

However, if you notice that your baby is having constant diarrhea or watery stools, especially after feeding, it’s time to change their formula. 

2. Excessive fussiness

Being fussy sometimes is a normal trait for all babies, but when it becomes more frequent than normal, this is often a result of being hungry or unsatisfied. 

It can also indicate that their body is uncomfortable or they're otherwise in pain, which brings us to the next point.

3. Gas

Along with changes in bowel movements, like having diarrhea after eating, an increase in gassiness can also be a sign that your baby’s formula isn’t agreeing with them. This may be accompanied by abdominal bloating and firmness of their belly. 

If this is the case, it’s a good idea to get in touch with your pediatrician to determine the best next steps and see if there’s anything else you can do to help alleviate your baby’s gassiness. 

4. Trouble sleeping

Along the same lines of things that can cause your baby to be fussy, being uncomfortable or hungry can also interrupt normal sleep patterns. Babies are supposed to sleep a lot in the early months of life, so if they’re not and this feels off to you, it could be a formula issue. 

Especially when trouble sleeping is paired with general fussiness and other signs of discomfort or discontent during the day, it’s important to consider how their formula may be contributing. 

5. Rash

Baby skin is very sensitive and can change daily depending on the environment. For instance, if it’s hot, humid, or cold, this can all impact the appearance and texture of the skin. 

Reactions to formula can also cause skin changes, like rashes form. If you notice a new rash forming and you’re not sure what could be causing it, it’s always best to speak with your child’s pediatrician. It’s possible that the skin could be reacting to formula and require a change. 

6. Wheezing after eating

If your baby is wheezing after they eat, this is generally an indication that the formula is causing mucus to build up and irritate their chest. If this is the case, this is not a normal response to eating and a formula change would be warranted.

Plus, reactions like wheezing or a rash can indicate that your baby is having an allergic response to something in the formula. Common allergens can include cow’s milk and soy. This reaction may be a sign of a more serious issue, and if your baby is showing signs of difficulty breathing when eating it’s important to get them medical attention immediately. 

7. Vomiting

All babies spit up after eating at some point in their infancy, particularly when they first start taking the formula and/or breast milk. This is normal. What’s more indicative of a possible formula issue is when the baby is regularly vomiting after a meal and is uncomfortable with it. 

For instance, if your baby is forcefully vomiting in a way that shows its body is trying to rid itself of something. This is a more immediate cause for concern, as vomiting their formula isn’t just discomfort to your baby but is also preventing them from getting the nutrients and fluids they need from meals.

What Are Some Baby Formula Options?

What Are Some Baby Formula Options?

When you make the decision to switch your baby to another formula, the most important thing is that you choose an option that you feel good about. Supporting brands you trust and ingredients you’re comfortable with are big pieces to consider when you’re comparing different formulas out there. 

A few of the most common baby formula options, when it comes to ingredients, include: 

  • Cow’s milk: This is the most common type and is generally iron-fortified. However, this option isn’t appropriate for babies with a milk protein allergy or lactose intolerance.
  • Soy: This is a good option for plant-based families or for babies who have a cow’s milk allergy or intolerance. 
  • Protein hydrolysate: This option is made with protein that has been more broken down than usual, to make it more digestible for babies. 
  • Sensitive formulas: This is an option most commonly recommended for babies who are spitting up, have more gas than usual or are experiencing a lot of overall fussiness. These are generally milk-based, easily digested formulas that may have other ingredients, like omega-3s, that are designed to help support sensitive tummies. 

What Should I Know About Switching to a Sensitive Formula? 

When switching to a sensitive formula, there are a few things to remember. The symptoms discussed above, such as diarrhea, extra gassiness, general fussiness, and discontent, are often signs that your baby needs to try a sensitive formula. 

While most babies tolerate a standard formula with no major issues, this doesn’t mean anything is wrong with your baby if that’s not the case for your family. 

Many babies are sensitive or intolerant to lactose or not accepting plant-based soy formula well; most of the time, you can address this issue by making a sensitive switch.

What Should You Do Before Switching? 

What Should You Do Before Switching?

Before you switch formulas, always speak to your child’s pediatrician to make sure they have been properly examined for any other potential health concerns. 

Additionally, they may recommend a specific type of formula to try first, based on the one that you’re trying to wean your baby away from. 

The pediatrician may also recommend that you speak with a registered dietitian who specializes in pediatric nutrition. Plenty of parents and babies need help with formula-changing needs, so you can rest assured that they come with a lot of experience and expertise in this area. 

How Do I Safely Switch to a Different Formula? 

How Do I Safely Switch to a Different Formula?

When switching your baby to a brand new formula, it’s important to take it slowly so as not to inadvertently create more problems by doing so.

Big feedings, even when your baby is feeling hungry, can exacerbate symptoms. Instead, try to feed your baby in small amounts in a more frequent feeding pattern, and increase the volume gradually as tolerated. Feeding in a slow progression is best. 

As part of the formula-changing process, you can also try applying gentle pressure to your baby’s stomach to help alleviate any gas buildup. This can be done with your hands or during tummy time on the floor. Be sure to wait at least 30-60 minutes after a feeding to do this to allow enough time to digest the formula. 

Overall, there are many signs that may indicate your baby needs to change formulas, ranging from fussiness to skin changes, or digestive issues. The best way to determine whether a formula change is appropriate, and decide which one makes the most sense to try instead, is to speak with your pediatrician or pediatric dietitian for individually tailored guidance. 


The content and advice provided in this article is for informational purposes only and is not a substitute for medical diagnosis, treatment, advice for specific medical conditions. Always consult a pediatrician to understand the individual needs of your child.

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