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Infant Feeding Guide: Is it Safe To
Mix Breast Milk and Formula?

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If you are here to ask if you can mix breast milk and formula, then the answer is yes! Here’s how you can safely mix both to feed your baby.

There are many instances when breastfeeding parents consider supplementing their infant’s feeding. If you are one of them, there are a few things that you must fully understand before you experiment with it. 

The most common scenario is when parents willingly mix breast milk with infant formula. If you didn’t already know it, you can, but only if the two are combined following proper guidelines. 

Inaccurate mixing can be harmful to infants- which is why you must read this guide about mixing breast milk and formula to feed your child safely. When in doubt always consult your pediatrician.

Reasons To Mix Breast Milk With Formula

There are multiple reasons for parents to choose to mix breast milk with formula. Sometimes, your baby will not just drink that formula, even if it tastes better than breast milk. Other times, the supplement’s formula does not suit your baby, too, so you want to make that transition easy by adding breast milk to it. However, parents need to check what the ingredients of their baby formula are made from. For example, you obviously will choose to feed infant formula without corn syrup.

Coming back to the reasons, the fact that it is a safe option to mix the two is a huge relief for most parents. Let’s look at the prime causes of mixing formula with breast milk. 

  1. Extra Sleep

Waking up every 2 hours to feed your infant is not easy; in fact it doesn’t let you sleep for months. Parents who want to get back to their regular sleep routine often start pumping breast milk or formula feeding to get extra sleep. 

The best part about this is that parents take turns waking up, so both are getting improved sleep, comparatively. 

  1. Low Milk Supply

Often, mothers face lactation problems where their milk supply is insufficient for the baby’s growth. Even after trying lactation therapies, mothers cannot produce enough to continue exclusive breastfeeding. This is probably the most common reason for most parents to mix breast milk with formula. 

For those cases, supplementation is the next best option. Using a formula to meet your child’s nutritional demands is not uncommon. 

  1. Returning to Work

This one’s an apparent reason. Working mothers have to return to work after their maternity leave expires. They can’t come home to nurse the baby on demand. Parents find it easier and manageable to choose a combination of formula and breast milk to slowly transition their babies into formula exclusively.

Safety Guidelines

It’s vital to adhere to the set of safety guidelines for you to follow to ensure that you are not causing any harm to your baby by mixing it improperly. Let’s look at the step-by-step process of mixing formula with breast milk. 

  1. Formula Preparation

If you have been using a concentrated formula, also known as powdered formula, the first thing to do is prepare everything according to the instruction. 

Make sure you read the packaging properly and use the correct amount of water and formula. Please be extra careful when you do this, as it can seriously damage the baby otherwise.

Once you have carefully mixed the right amount of drinkable water into the formula, gently pour in the breast milk. 

Tip: Never use breastmilk instead of water while preparing the formula. You must maintain the correct ratio of water: formula, and it is only safe to include breast milk to the formula afterward. This ensures that you are not hampering the nutritional mix of the formula. 

If you add excess water to the formula. In that case, it will dilute its nutrients, while reducing the amount of waste can damage your child’s digestive tracts, and kidneys, leading to severe dehydration and neurological issues. 

For ready-to-drink liquid infant formula, there are no additional steps that you need follow, you can just add the breast milk to it directly. 

  1. Storage and Disposal

This is crucial. Storage and disposal rules vary for breast milk and formula, so you need to know exactly how to store each of them and dispose of them accordingly. 

It’s safe to freeze breast milk using a food-grade plastic container for up to six months. Once it has been thawed, it can only be kept in the refrigerator for up to 24 hours. 

If you have freshly pumped breast milk, you can keep it in your refrigerator for up to 5 days. Another way to store fresh breast milk is to use an insulated cooler, but only for up to 24 hours. 

If you have already opened the container for liquid formula, you must refrigerate it immediately. Best to use it within 48 hours of opening it. For premade formula bottles, you should use them the same day. 

Similarly, a bottle of breast milk combined with formula can only be kept in the fridge for up to 24 hours. Discard it once it has been over a day in the fridge. Please do not try to feed it to your child. The best tip anyone will give you is to write the time on the bottle using a label or sticker to ensure it’s safe.

Freshly pumped breast milk can also be kept at room temperature, but only for up to 5 hours. However, a bottle mixed with formula and breast milk in room temperature should be discarded after an hour. 

Benefits & risks


Mixing formula and breast milk in the same bottle has the benefit of making feedings more convenient for parents.

There are additional advantages to this combination of mix feeding as well:

  • Your infant is likely to adjust to the changed taste quicker. If your child has been exclusively breastfed, there is a big chance that he/she will reject the taste of formula. But if you mix them, and gradually increase the portion of the formula, your baby’s transition from breast milk to formula will be smoother. Remember, infants don’t welcome unfamiliar tastes, so taking baby steps is the way to move forward. Trust us; you don’t want a jittery, cranky, and fussy baby
  • Another top benefit of mixing the two, as mentioned, is that the parents and baby both get to sleep for extended hours. Usually, babies find it easier to digest breast milk than formula. Infant formula takes longer to be processed by infants, so their sleep is also stretched when fed formula mixed with breast milk.

Risk Factors

Unfortunately, there are potential risk factors to combing formula with breast milk. Let’s look at some of the consequences of mixing the two in one bottle. 

  1.  Wasting Breast Milk

Breast milk is another name for liquid gold. This is how valuable it is to parents of infants. Mixing it with formula opens up the chance of it going to waste. Pumping breast milk requires time and effort. So, when you see your hard-earned liquid gold going to waste, it’s not nice. 

If you don’t want to waste your breast milk, feed them breast milk exclusively first. If you feel they are still hungry, offer them a formula bottle. 

  1.  Reduction in Milk Supply

This is a heartbreaking repercussion of mix-feeding your child. Once you have added formula to their routine, you are actively producing less milk, which leads to a reduction in your milk supply. But if you choose to supplement slowly, you can still maintain your milk supply for months. 

  1. Potential Health Risks

As mentioned above, it’s mandatory to check that you are preparing your baby’s formula, as per the instructions.

Once again, refrain from using breast milk as a substitute for water when mixing powdered formula. Note that mixed formula with breast milk is not supposed to last, it has a shorter shelf life, in comparison to breast milk alone. 

Final tip: Mixed bottle of breast milk and formula must be disposed of within an hour of the first use. 


It’s not necessary for breast milk and formula to be mutually exclusive. Babies grow perfectly from breast milk, as well as with formula. Mixing breast milk with formula will also give them adequate nutritional benefits. There’s no right and wrong here, as long as you are ensuring safe feeding.  

You could nurse, pump, combine or do alternate breast milk and formula feedings. You have to figure out what works for you and baby!

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