Your Guide to Switching Baby Formulas: Reasons, Tips & Side Effects You Should Know

Are you thinking about switching baby formulas? Formula changes happen for many reasons, from allergies and medical issues to formula recalls and brand preferences. Babies can often switch formulas with no problems, even if the change has to happen immediately due to unforeseen circumstances.

You may be wondering if you can switch formulas quickly or how long it takes for a baby to adjust to a formula change. These are totally normal questions and important considerations as you make the switch!

We spoke to Lauren Crosby, MD, FAAP, and Bobbie Medical Advisor, to get answers that can help you transition confidently. She shares her steps for making the change and assures us that, yes, a formula switch can happen cold turkey.

Reasons to switch baby formula

Maybe your little one is experiencing sensitivities to your current formula, or perhaps you simply want to try another kind. There are several reasons you may consider switching:

Recalls and/or availability issues

While rare, formula recalls do happen. One of the benefits of using a U.S.-based formula is that recall information is typically widely shared via email and social media. Recalls can also impact product availability in stores and online, and sometimes a formula switch may be necessary if the product you usually use is out of stock.

Convenience and cost

Many families switch formula types based on convenience, cost, and availability. Ready-to-feed formula is just that: ready to feed directly from the bottle. It’s sterile, making it the best choice for premature or immunocompromised babies, and it’s incredibly convenient for travel and on the go. The downside, however, is that ready-to-feed formula can be a bit pricier than powdered formula.

Another, lesser-known option is liquid concentrate formula, which typically comes in cans or tetra-paks. Because it just needs to be mixed with water (usually at a 1-to-1 water-to-formula ratio), it’s extremely convenient. While also potentially expensive, on average, it’s cheaper than ready-to-feed.

Many infants can switch between these types of formula without issue. But be aware that some brands have different ingredients across powder, ready-to-feed, or concentrate products, even if the product name is the same for each.

Going organic

While both organic and non-organic formulas meet FDA regulations for nutritional composition for infants, organic formulas limit the use of:

• Synthetic pesticides
• Antibiotics
• Growth hormones

If parents prefer an organic baby formula, most babies can switch without issue as long as the key ingredients (protein type/size and carbohydrate source) are similar between the two products.

Personal choice

Your needs matter, too! If a formula doesn’t work for your budget, values, religious requirements (i.e., must not use certain animal by-products), or any other reason, you might consider trying another formula option.

Pediatrician suggestion

It’s important to communicate with your doctor before switching baby formulas, as these trained professionals have more insight into what may be causing certain symptoms. Your child’s doctor may recommend a switch based on the following signs:

Diagnosed condition: A diagnosed condition, such as FPIES, GERD, or metabolic disorders, may necessitate a formula switch to treat symptoms.

Diagnosed allergy: Cow milk–protein intolerance is reported in 2% to 5% of infants within the first one to three months of life, according to the American Academy of Pediatrics. If your baby was diagnosed with a milk allergy via a stool test or based on symptoms, you’ll need to switch to a hypoallergenic formula. 

Blood in stool: Blood in your baby’s diaper is never a good thing, but don’t panic. Whether visible or hidden (occult), this typically means you’ll need to select a hypoallergenic formula due to a food sensitivity or allergy.

7 things to try before switching baby formulas

Before you switch formulas, it can be beneficial to try a few strategies first. Often, parents assume that formula is the cause of a problem when, in reality, their baby may be experiencing normal infant digestive symptoms. In many cases, a simple switch in bottles, feeding methods, or the addition of a probiotic supplement can make an enormous difference.

Try these methods before jumping to an entirely new formula:

1. Paced feeding

Sometimes called “responsive feeding,” paced feeding is a method for bottle feeding that better mimics feeding at the breast. Paced feeding strategies allow the baby to control the flow of breast milk or formula, which can help minimize:

• Excess air intake,
• Gulping of milk or formula
• Overfeeding

2. Probiotics

The good bacteria found in a probiotic supplement can support the growth of healthy gut flora in your baby’s digestive tract. Some probiotics are also clinically shown to reduce colic symptoms. Discuss probiotics with your pediatrician before using them, as they are not recommended in some cases, including for extremely premature infants.

3. Gripe water

Gripe water is an herbal supplement that may offer relief to babies who suffer from gas, colic, hiccups, or general fussiness. Gripe water is a homeopathic remedy without much clinical data to support its use, so be sure to discuss it with your pediatrician before offering it to your baby.

4. Anti-gas/anti-colic bottles

These bottles are specially designed to decrease your baby’s gas pain and discomfort by reducing air intake during bottle feedings. Look for a bottle that offers some sort of venting system within the bottle itself, collar, or nipple to prevent your child from taking in extra air during feedings.

5. Baby massage

A gentle massage on an infant’s tummy can help encourage trapped air to move through the intestines and relieve gas pain and discomfort. Gentle strokes in a clockwise or counterclockwise motion may help, as can helping your baby do alternating “bicycle legs.”

6. Sleep intervention

Many symptoms of digestive distress can mimic those of overtiredness, particularly crying, fussiness, and symptoms of discomfort. Make sure sleep is on track before switching formulas, outside of obvious symptoms of allergy or intolerance.

7. Decrease nipple flow

Finding the right nipple flow rate can be crucial in addressing digestive discomfort. A nipple flow that’s too fast can result in gas from gulping milk or formula too quickly, as well as reflux and overfeeding.

How to switch baby formulas: From gradual to cold turkey

If you’re ready to make the switch, timing is everything. Dr. Crosby shared her guidance on how and when to try a new formula:

“If your child is on a cow milk-based formula, you can typically switch right over to another cow milk-based formula. If your child is on a special partially-hydrolyzed or hypoallergenic formula, you will want to switch to a new formula that has the same protein structure — either partially-hydrolyzed (gentle) or extensively-hydrolyzed (hypoallergenic).” 

She explains, “Some formulas are more appropriate than others for infants with an allergy, so if you are not sure what is equivalent, definitely check with your child’s doctor.”

“If you’re transitioning and have some of the old brand left, you can start by mixing three parts old formula and one part new formula. If the baby drinks it, move to half and half and then 1/4 old and 3/4 new. Following that would be a full bottle of the new brand.”

Can you switch baby formulas cold turkey?

“In a situation with recalls, poor product availability, or allergy symptoms, parents may need to pivot to a different formula quickly — and that’s perfectly fine to do. You can start with an equivalent formula ASAP,” says Dr. Crosby. 

Switching baby formula brands quickly is safe and well-tolerated in infants. There are no advantages to gradually switching from one formula to another versus switching immediately.

Switching baby formulas side effects

Typically, if you’re switching to the same type of formula (e.g., routine, gentle, or hypoallergenic), there shouldn’t be any significant side effects. Some babies are more sensitive to change than others. They might dislike the taste, or they might spit up more.

Poop consistency might change, too. Babies might:

• Poop less often
• Poop more often
• Have runnier poops
• Experience a change in stool color
• Be gassy and fussy

It can take a week or so for a baby to adjust to the change, but if the symptoms aren’t causing much distress, it’s OK to give it some time. If you have any concerns about the side effects of changing formulas, reach out to your baby’s pediatrician, and they can let you know what’s normal.

Switching baby formulas FAQs

How long after changing baby formulas do you see side effects?

Usually, 7–10 days is enough time for a baby to fully transition to a new formula. You can monitor your baby’s symptoms to make sure the new formula isn’t causing any unwanted effects.

Some babies take to a change easily, while others’ tummies need time to adjust. It’s a good idea to monitor your baby’s formula intake, poop consistency, sleep schedule, spit-up, and skin changes, and look for blood in the stool. If you see anything concerning, give your pediatrician a call.

How long does it take a baby to adjust to a new formula?

Sometimes, when changing formulas, babies will notice a difference in taste, which is more common with older babies. Often, they get used to a new formula quickly. However, if they’re giving you a hard time, you can wait until they’re sufficiently hungry to try feeding, as they may be more accepting of the change.

How long does it take to transition baby formulas?

One to two weeks is a good transition period, depending on how the baby is doing and how quickly you feel comfortable making the change.

How can I tell if a formula isn’t working for my baby?

These symptoms could mean that your formula isn’t agreeing with your baby. Speak to your pediatrician if you notice any of the following signs:

• Spitting up more than usual and/or projectile vomiting
• Not drinking enough formula day after day
• Hard, pellet-like poops
• Watery or foamy poops
• Blood in the poop
• Increased crying or fussiness that doesn’t respond to soothing strategies
• Skin rashes or hives
• Poor weight gain or weight loss

What are the signs and symptoms of an allergy to formula, like a cow’s milk allergy?

If you suspect an allergy, you should see your baby’s doctor to discuss your concerns and have your baby weighed and examined. It’s a good idea to bring a fresh poop sample to the doctor’s visit to be examined.

Allergy symptoms may include:

• Spitting up more than typical
• Poor appetite
• Projectile vomiting
• Not gaining weight well
• Watery poops
• Blood in the poop
• Increased crying or fussiness that doesn’t respond to soothing strategies
• Not sleeping well
• Skin rashes

When should you switch to different baby formulas?

Talk to your pediatrician to see if it’s time to change to a gentle or hypoallergenic infant formula if your baby:

• Is very fussy or spits up constantly
• Isn’t gaining weight or feeding well
• Has blood in their stool
• Is very gassy
• Sleeps poorly because they seem to be uncomfortable

There are different types of formulas depending on the baby’s symptoms. Some are hypoallergenic, meaning the proteins are extensively broken down so they can be digested more easily without triggering an allergic response. These are for babies with a diagnosed cow’s milk protein allergy.

Other formulas contain partially hydrolyzed proteins, which could work for babies experiencing gas and/or fussiness, but not a true milk allergy. Some formulas are made for “lactose sensitivity,” but babies in general don’t have lactose intolerance (as lactose is the primary carbohydrate in breast milk, regardless of whether a mom consumes dairy products). Typically, if a formula helps, it’s because it also has some of the proteins broken down for easier digestion.

When should you switch formulas because of gas?

Often, parents think gas is the reason their baby is fussy, but that’s not always the case. Fussiness can be caused by several different factors.

If your baby cries a lot, then passes gas and seems relieved, gas is likely the issue. If these episodes don’t occur often and are over quickly, then it’s fine not to do anything as long as the baby is growing well, pooping, happy, and sleeping. If you think your little one is gassy, try a different type of bottle or nipple and make sure they burp well. 

Your pediatrician may recommend an over-the-counter gas remedy as a next step, and if that doesn’t help, they might recommend a formula switch.

Is it bad to keep switching baby formulas?

It can take up to one to two weeks for a baby to fully adjust to a new formula. When possible, try to avoid switching formulas during this transition period. Too many changes in a short period can increase digestive upset and cause symptoms that may falsely indicate that your baby isn’t tolerating a formula well.

Switching baby formulas the right way

Whether you’re exclusively formula-feeding or supplementing with formula, there are many reasons a formula switch may happen. It could be because of an allergic reaction, your personal preferences, a recall, or an availability issue. In general, switching is completely safe!

As always, please involve your baby’s healthcare provider so you can get guidance on how to switch and which formula is best for your baby.

Want to test out a trusted brand? Bobbie Organic Infant Formula is designed to give your baby the nutrients they need for healthy growth. With DHA, choline, iron, lactose that naturally provides prebiotic properties, and other essential ingredients, you can rest assured that every sip is supporting your baby for years to come.