The need to change your baby formula is quite common. New babies, new moms, new formulas and new ingredients— sometimes what’s new works well together, and sometimes it doesn’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 baby formula 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 baby 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 the top reasons to change baby formula:

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 formula at each feeding – Formula is getting expensive

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 baby formula may be more nutritious

As times change and production gets better, some moms may notice that a new type of 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 baby formula with a 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 baby formulas?

So, how do you go about actually switching baby formula brands or types?

You should consult a health care professional 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 they 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 to switch baby formula 

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.

You can 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 for changes
  • Check 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 baby formula?

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 for your infant 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 parenting sources have cited that it may be okay to mix the two formulas if you are switching for preference (versus an allergy). For instance, changing from a non-organic to an organic baby 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 should run this by your pediatrician for more clarity.

How long does the change take?

The pressing question is 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 or a change for the flip side of things.

Sometimes, you may not notice a change and that is ok and even welcome. If you’ve switched your baby to an organic formula – you may not physically or immediately see any changes, however, but 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 should try the formula for 8-10 days. Again, don’t hesitate to contact your doctor for any reason. It is also normal to be concerned and all of 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 your pediatrician.

To that end, don’t throw out all of your earlier 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.

Summary about switching baby formula

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.

The content on this site is for informational purposes only and not intended to be a substitute for professional medical advice, diagnosis or treatment. Discuss any health or feeding concerns with your infant's pediatrician. Never disregard professional medical advice or delay it based on the content on this page.
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.