The need to change your baby formula is quite common. New babies, new moms, added to new formulas – new ingredients sometimes new simply work together, and sometimes they don’t. In such a case, we go back to the drawing board and try to find the best way forward. 

Good news, babies can change formulas from time to time with little to no issues. So, if you are looking to change formula for health concerns or because you want to switch from say non-organic to organic then you will be able to do so. As for an answer to the question ‘how long does it take for baby to adjust to formula change?’, we will delve into the research to see what it says and help you figure out what you can expect if you need to make a swap. 

Reasons to Change Formulas

If you’re already using formula consistently (either fully or as a supplement to breast milk), you might wonder why someone would want to change formulas in the first place. But, there are plenty of reasons why it could be wise to change your baby’s formula. Here are a few: 

Baby reacts to formula in a negative way

When it comes to your little one, it’s hard to know what works and does not work for your baby. In most cases, it’s a matter of trial and error. Some new moms might find that while the baby accepts a particular formula brand, later on, they notice some form of reaction. 

Allergic reactions may be a common sign that your baby is having a negative response to the formula. However, in order to know for sure, you should contact your healthcare provider. 

Furthermore, some mothers might find that their baby starts to react more outwardly negative toward a given formula. Babies may cry, get gassy, spit up or experience unfavorable bowel movements, due to formula

Try to keep a close monitor on your baby and use a baby journal to record whatever you may notice. While the above may be symptoms of a reaction to the specific baby formula, you will need to talk to an expert to confirm. Any signs of issues with your baby should always be taken seriously and acted upon. 

Baby requires more at each feeding – Price Concerns

Infant formula can be pricey, especially as you’re looking for the best formula for your baby. As babies grow to the six-month mark, they progressively need more and more formula until they start consuming solid foods alongside liquid foods. 

Until that point, parents can be overwhelmed with the cost of baby formula. They might find a suitable replacement that has the same nutritional content but is cheaper overall. In this case, it may prove financially wiser to make the switch to the cheaper, but still worthwhile, formula.

Another Formula May Be More Nutritious

As times change and production gets better, some moms may notice that a new formula seems more nutritious or will better serve their baby’s needs than their current formula

Alternatively, they might meet up with their pediatrician and be given a directive to find a new formula brand that has more of a particular nutrient, vitamin, or mineral. For instance, as their baby gets older, doctors may recommend the need to pursue a formula with a bit more iron or the like.  

Whatever your reason, remember that it’s very much okay to switch formulas and it is a normal part of the process. 

Before getting further into this topic, it may be fair to say that no two infant formulas are made the same, however, you may want to still ensure that you do not experience the same issues after switching which is why the next point is so important.

How to Change Formulas

So, how do you go about actually switching formulas? 

You should consult a trusted caretaker or your loved one before making a switch. Your baby’s health care professional is just that – a professional. They would’ve advised other mothers on how to switch formula dozens of times before and they might have their own tips to share regarding the process and making it a smooth one. They will also be able to give you direct pointers regarding which formulas you should look for. 

Once you’ve spoken to your baby’s doctor and found a suitable replacement, don’t expect things to change overnight. Babies can be pretty fussy and love their routines – so adjusting may take some time. All is needed is a little more time and some patience on your part. 

Use a gradual process 

You should introduce the new formula slowly if your baby is picky with bottle feeding. Try to give them a little bit of the new formula during the middle of the day, or whenever your baby is historically happier or calmer. This keeps your little one grounded and feeling like their world isn’t changing too much or too fast.

This being said, you can always switch formulas right away if needed. It all depends on your little one and their personality or sensitivity. Or, if the need to switch was due to health or allergy concerns. 

However, switching gradually instead of right away may be a good choice. You should feed your little one more of the new formula over time and keep an eye on how their body handles the change. 

  • Check their demeanor and even their diapers for any significant changes. 
  • Monitor how much food they continue to eat. 

If all seems good, continue to increase the new formula amount until it’s replaced the old formula entirely.

Should You Mix Formulas?

In most cases, it is not advisable to mix two formulas. Mixing formulas can be tricky when you’re testing to see if the new formula works well with your infant’s body. Or if you are switching formulas due to allergic reactions. 

When formulas are mixed it may be difficult to tell whether the old formula is acting up again or if the new formula is to blame. Plus, some formulas just don’t mix well together.

However,  some sources have cited that it may be okay to mix the two if you are switching for preference. For instance, changing from a non-organic to an organic formula. You may be able to add one scoop of one with a scoop of the next just until your baby adjusts to the formula. You can always run this by your pediatrician for more clarity. 

How Long to See a Real Change?

The pressing question was how long does it take for baby to adjust to formula change? In most cases, it can take about a week to ten days for a new formula brand to fully settle in your child’s digestive system. You might get an immediate response from your baby in terms of flavor or preference, but it’ll take at least a couple of weeks to see actual improvement if at all or, even a change for the flip side of things. 

Sometimes, you may not notice a change and that is okay and even welcomed. If you’ve switched your baby to say an organic formula – you may not physically or immediately see any changes, however, within you know that the switch was for the best – based on your definition.  

Of course, if you’re switching formulas because the last type of formula was causing health concerns, improvement should be immediate whenever you switch. This is especially true if your baby has a milk allergy to cow’s milk and you are switching to a hypoallergenic formula or a soy formula. 

Talk to your doctor if things don’t improve after using a formula to take care of any allergic reactions or the like.

Other Things to Consider When You Switch Formulas With Your Baby

It’s not uncommon for babies to have strange digestive reactions to things. Their bodies are simply more sensitive, so even a formula that will eventually end up settling with their system could cause minor issues at first. This is normal, so you have to stick with it for up to 8-10 days. Again, don’t hesitate to contact your doctor for any reason. It is also normal to be concerned and all your questions are valid. 

If you notice any concerning reaction post switching, you may certainly cease the new formula and go back to the old formula until you find a better solution – while voicing your concerns.

To that end, don’t throw out all of your old formula when you get the new brand. You may need to go back to what you and your baby know, at least temporarily, until you make sure that new formula is exactly what’s right for your situation and your baby’s unique needs.


All in all, it can take your baby some time to adjust to a new formula, but the exact timeframe will vary from infant to infant – up to 10 days is a good time frame if you are noticing adverse effects. Expect to spend that amount of time both getting your baby used to the new formula and waiting for their body to give you a sign that everything is running smoothly. 

Gradual progress and change are to be expected, so don’t worry if the improvement isn’t immediate. Keep in regular contact with your doctor and update them on the progress of the switch so they can assist you if anything more serious comes up.

When it comes to formula feeding your baby, every answer is unique. That’s why we’re always here if you have other questions about formula or other motherhood needs. Let us know how we can help!

Bridget Reed, contributing writer for Milk Drunk with the expert advice of Dr. Jacqueline Winkelmann, board-certified pediatrician awarded Top Pediatrician by the International Association of Pediatricians: Leading Physicians of the World in 2018.

Bridget Reed is an experienced writer, editor, and SEO content manager. She graduated with her bachelor’s in business management and organizational leadership and is a proud mom of three.

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