How Long Does It Take for Baby to Adjust to Formula Change?

How Long Does It Take for Baby to Adjust to Formula Change

In most cases, it will take a baby about a week to ten days for them to fully adjust to a formula change. Note that you might immediately get a reaction from your baby concerning this change of formula.


This is mostly due to the flavour of the new formula or your child’s preferences. But as pointed out earlier, it will take a couple of weeks for your baby to get used to the new formula.


There are multiple reasons that may force you to change your baby’s initial formula. Whichever the case, it would be best to understand more about baby formula and that’s what this guide can help you with.


What is Baby Formula?

Baby formula is manufactured food, which is designed, marketed, and sold for feeding babies and infants. Usually, baby formula is perfect for children under 12 months and it’s prepared for cup or bottle-feeding.


As for the ingredients available in the baby formula, they may vary because of brand and even country. However, the common type of baby formula contains processed skimmed cow’s milk.


In addition, the skimmed milk contains stabilisers and emulsifiers. The two components facilitate the mixture between the oils available in the formula and water. This is highly necessary considering that you have to prepare the formula with water.


Other than that, baby formula may also contain the following contents:

  • Plant-based oils – These include palm, coconut, rapeseed, soybean oil, and sunflower
  • Fatty acids – These are usually derived from fish oil
  • Minerals and vitamins – Usually from animal and plant sources
  • Enzymes and amino acids
  • Lactose – Lactose is a natural sugar that’s usually found in the milk. It’s also available in fructose and corn syrup, among other products
  • Probiotics – These have various health benefits but they aren’t available in all baby formulas


You should also know that different types of baby formula will contain different mixtures of ingredients. Therefore, it would be unwise to think that all types of baby formulas have the same mixture of ingredients.


Research shows that there are 1000+ proteins in a mother’s breast milk. So, most if not all, formula companies are ambitious about increasing the protein content in their formulas. When it comes to the cow’s milk, there is a need to add excess protein in the formula.


This is because the level of protein present in the formula needs to increase the amino acid concentration to the level that your baby needs. As for the excess protein available in formulas, it can be metabolised and broken down into fat.


Different Types of Formula

As you may know, there are three different types of baby formulas. They all differ in terms of ingredients, composition, and reasons for use. If you have a new-born or you’ve just adopted an infant, then these three types of formulas can help you feed the baby well.


However, it would be best to first seek paediatrician’s advice before choosing the formula to feed your baby. With that in mind, let’s look at the different types of formula on the market:


  1. Cow Milk Protein-Based Formulas

Starting us off, this is the most common type when it comes to baby formulas. Cow milk protein-based formulas are also the most used types of baby formulas by most parents. So, what makes this type of formula the most preferred?


First, cow milk-based formulas are created to emulate a mother’s breast milk. With this type of formula, your child will get a nutrient balance feed that’s easily digestible. As mentioned earlier, this is the most consumed type of formula.


However, babies that are allergic to the cow’s milk can’t consume this type of formula. Hence, they need an alternative diet, which may be either of the remaining two types of formula.


  1. Protein Hydrolysate Formulas

Unlike the cow and soy baby formulas, the protein hydrolysate formulas have proteins that have been broken down into smaller sizes. If your child is allergic to either soy or cow formulas, then this will be a great alternative for them.


  1. Soy Based Formulas

Soy based baby formulas don’t have any animal products in their composition. They exclude all animal products and can also be perfect alternatives to cow or protein hydrolysate baby formulas.


Changing Baby Formula Side Effects

There are several reasons (with allergies being on top), that might cause a parent to change the formula that their new-born was initially using. If you decide to change your baby’s formula, then you must have a good reason for doing it.


Note that there is no fault in that, only that your child will have a high chance of experiencing side effects from using the new formula. This is because your infant will be transitioning from what they were initially accustomed to, and on to a new formula.


The side effects will vary depending on your child’s allergies, preferences, and what the new formula contains. So, what are some of the side effects of introducing your baby to a new formula?


Let’s find out…


  1. Rumbling Tummy

If unaware, stomach upset is the most common side effect experienced by most babies after a change of formula. Because your child was used to one formula brand for some time, then their digestive system will need some time to adjust to a different brand.


In most cases, it might not even be something to worry about but it is good to keep a closer look at your baby during the formula change experience.


  1. Allergies

Like explained earlier, allergies are the common causes for changing the initial formula for most babies. With that in mind, your child may as well experience negative side effects caused by changing the formula.


The following are some of the signs that your child is allergic to a new formula:

  • Vomiting
  • Diarrhoea
  • Skin rash
  • Abdominal pain
  • Blood stains in stools


  1. Spit Up

When consuming a new formula, your infant may spit-up as well. This might be a sign of stomach upset, which is a common reaction soon after most babies have a change of formula.


That said, the three side effects explained above are the most common types when it comes to side effects after changing your baby’s formula. Note that crying, drooling, or requiring a burp after eating might cause your child to spit-up.


If that is the case, then there is no need for alarm according to However, you should be concerned if the explained side effects persist without your baby crying, drooling, or needing a burp.


How Long Does It Take for a Baby to Get Used to a Formula Change?

The duration it will take for a baby to adjust to a formula change varies from infant to infant. But like explained earlier, most infants need about a week to ten days to fully adjust to using a new formula.


Nevertheless, it would be best to monitor your child closely during this process because the duration will depend on several factors. First, switching from powdered to liquid formula of the similar brand won’t require an adjustment period from your baby.


The case is different if you are switching from cow’s milk formulas to soy-based formulas. This is because the baby will need some time to fully adjust to the new ingredients in the soy-based formula.


Depending on the reasons, it would be best to wait at least a maximum period of two weeks in between changes. This is to help your baby avoid too much turmoil in his/her stomach, while adjusting to the new ingredients effectively.


How Long Does It Take to See Results in a New Formula?

Like most of us, young babies will experience changes in their systems differently. This will happen even if two babies are introduced to the same formula and due to similar reasons as well.


Remember, your child’s digestive system or metabolism intake might not be the same as others. So, it wouldn’t be accurate to assume a standard duration to experience results after changing the formula for every baby.


But by estimation, most studies show that it will take about 2-6 weeks for parents to notice a change in their baby after switching the formula. That duration isn’t constant and it might be affected by many factors.


In some cases, your child might not even need six weeks under their belt to start showing your signs of change. This is especially the case when switching to a new formula due to allergic reactions from the initial one.


If you switch to a new formula due to allergic reactions and notice that the symptoms from the previous formula are still persistent within 2-6 weeks, it would be best to seek medical attention.


Signs Formula Doesn’t Agree with Baby

There are many signs that show your baby might be taking the wrong formula. Fortunately, or may be unfortunately, these signs may easily start showing immediately after switching the formula.


Some of the signs and symptoms of a formula switch not agreeing with babies are:

  • Weakness or fatigue
  • Watery stool
  • Excess gas
  • Forceful vomiting
  • Scaly skin
  • Crying grunting
  • Uneasiness or fussiness after eating


Those are all the common indications that the formula switch isn’t going good for your baby. However, the aforementioned symptoms might also be a sign of another illness other than negative side effects of a formula change.


The best way to know is to track and even note down what your child starts exhibiting immediately after taking the new formula. If unaware of the exact time when your baby started experiencing such symptoms, then it’s best to seek professional assistance.


How Long It Takes a Baby to Adjust to Formula from Breast Milk

Ten days remains the standard duration for your baby’s digestive system to fully adjust from breast milk to formula. But as explained earlier, this duration will vary from one infant to another depending on several factors.


Therefore, you should observe your child closely and not assume that the duration is constant in every child, just as explained earlier. Additionally, it would also be inconvenient to introduce your child to formula just drastically.


Remember, their digestive system is still developing and might not be able to handle well the drastic changes. For this reason, you need to introduce formula to your baby in a way that won’t be as hasty but one that will also be effective.


Therefore, you can check with your paediatrician for the best advice on switching your baby from breast milk to formula. In addition, allergies and other factors will be significant determinants on how long it will really take for your baby to fully settle for formula.


You just have to be patient while following all the necessary protocols, and your child will be loving and getting healthy with the new taste of formula.


How to Know What Formula is Right for your Baby

This mostly comes down to noting the different things that occur after your child starts taking the formula. If the formula starts affecting your baby negatively, then that is a sign that your baby is allergic to the formula.


As stated earlier, there are many negative side effects that occur as soon as your baby starts taking a new formula. However, these effects may occur at different times in different babies.


So, if your child exhibits the negative effects stated earlier after switching formulas, it might not be the right one for them. And if you are struggling with finding the right formula for your child, seeking a paediatrician’s advice won’t be a bad idea.



The pressing question on how long it takes for a baby to adjust to formula varies in all children, just as earlier explained. But according to studies, most children will need up to ten days for their digestive system to fully adjust to formula change.


However, that estimation mostly assumes that all other factors remain constant. This means that you exclude allergies or persistent negative side effects brought about by switching from the initial formula.


Therefore, you should observe your child for a maximum of two weeks and keep track of the occurring changes after switching the formula. This will help you understand if the change has negative or positive results on your child.


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