Can You Mix Breast Milk and Formula?

Can you mix breast milk and formula? Do these two liquids play well together?

For such small creatures, babies spark a whole lot of questions.

And many of them have to do with how you keep them fed, hydrated, and rested.

So here’s one on the top of the list: can you mix breast milk and formula?

The short answer is yes! You can feed your baby formula and breast milk separately, and you can also mix formula and breast milk in the same bottle – carefully!

Here’s the scoop.

In this article: 📝

Can you mix formula and breast milk?

Returning to work, needing extra sleep, or being low on milk supply are all reasons you might want to combine breast milk and formula.

You might want to breastfeed at some feeds and offer formula for others.

Or perhaps you’ve been formula feeding and want to start breastfeeding.

Whatever your needs, there are ways to mix it up safely and ensure that your baby gets the nutrition they need.

The WHO recommends exclusive breastfeeding for the first six months of your baby’s life.

“Breast milk has everything necessary for your baby to thrive and actually can even change in response to what your baby needs at the time, explains Registered Toddler Dietitian and Nutritionist (RDN) Kacie Barnes.

However, infant formulas also contain everything that your baby needs to grow and develop – so for the first 6 months of life, one of these 2 choices will be their sole food source."

If you want to and it is feasible for your life, you can exclusively breastfeed for the first six months and keep the formula for later.

As well as providing your baby with their own custom-build super drink, breastfeeding frequently helps build your milk supply.

But sometimes, exclusive breastfeeding is simply not possible.

Health conditions like mammary hypoplasia may cause low or no milk production.

Receiving certain medical treatments like radiation therapy can also make breastfeeding a challenge, as can having postpartum depression and anxiety.

You may also have to be separated from your baby for a bit and need a substitute.

And some people simply choose not to breastfeed, and that is okay too.

Basically, there are so many reasons supplementing your breast milk may be necessary – and luckily, there are safe ways to do so.

Let’s have a look at the ins and outs of mixing it up.

How to start combo feedng

Though you can mix breast milk and formula in the same bottle (we’ll get to that later), it’s usually preferable to try other methods of combination feeding first.

Let’s take a look at the two most popular ways:

1. Breast milk, then formula

If you’re struggling with milk supply, the Nemours Foundation recommends that you nurse first, then try to feed your baby pumped milk from a bottle.

Formula can then make up the difference if you need to supplement your supply.

Getting your baby used to a bottle can take some practice.

It’s a whole new skill for them.

One option is to get someone else (a partner or caregiver) to give them the bottle first.

That way, they’re not near you smelling your breast milk.

Head here for our guide to bottle feeding.

And if you’re going in the other direction (from formula to restarting breastfeeding), know that there may be a bit of an adjustment period.

Be kind to yourself.

Some tips?

1. Express milk often

This stimulates a hormone called prolactin which helps out with your supply.

“Supply and demand helps regulate your milk,” explains Barnes, “so the more often you feed, the more information your body is going to receive to make more milk, so consistency and frequency are two helpers here.”

2. Cuddle your baby

We love getting instructions as adorable as this one.

This encourages your baby to feed and your body to produce milk.

“Hormones are powerful!” says Barnes”.

“There are actually hormones released when you look at and snuggle your baby, and those can aid in milk production!”

Giving them a bottle while maintaining skin-to-skin contact can be a great option as you transition.

2. Breast milk for one feed and then formula for another

Particularly if you are weaning your baby off breast milk and onto formula, this can be a good option.

Just remember to go slow so that you stave off the risks of your breasts getting engorged (that’s when they’re overfilled with milk, and it can come with a fair degree of pain and discomfort).

If you’re using this method because you’re going back to work or have other engagements where you need to be away from your baby for stretches of time, try to get in the swing of things a few weeks beforehand.

This will give your body and your baby time to adjust.

Paced bottle feeding is also a good idea here.

Basically: go slow. If the milk from a bottle comes out too quickly, they may get used to this fast pace and struggle to re-adapt to breastfeeding.

A slower feed means they are more in control, can feed slowly, and take breaks when needed.

But there might be situations where you want to mix formula and breast milk in the same bottle.

So, can you do that? Read on.

How much formula do I mix with breast milk?

Mixing formula and breast milk in the same bottle is possible, it must be done with care.

The basic principle here is to ensure the formula is ready to drink before mixing it with your breast milk.

So if you’re using a concentrated liquid formula or a powder formula, prepare it first according to the package directions with safe drinking water before adding it to a bottle with your breast milk.

Ready-to-feed formula is already diluted, so it should be already good to go.

Why is mixed feeding not recommended?

There are a few reasons to be cautious about making the mix.

Perhaps the most important one is that you don’t want to have too much nutrition in your baby’s diet.

When mixed with water in a specific ratio, formula is specially designed to meet the nutritional needs of your baby.

If you add formula straight to breast milk, the nutritional balance may be off.

And this can be dangerous.

Because your little one’s kidneys and digestive systems are still learning how to do their job, they may not be ready to process such a nutrient-dense mixture.

So, it’s important first to prepare the formula following the exact instructions on the packaging – and then add breast milk to that already-prepared mix.

(Here are the CDC’s guidelines on how to prepare formula safely.)

Another downside of this method is the potential for wastage of your precious breast milk.

You want them to get as much of the good stuff as possible – particularly in those first six months.

And if they don’t finish their bottle, you may have to say goodbye to some of the breast milk you’ve worked so hard to make.

“But it's also important to note that you can't always reuse breastmilk in the name of not letting it go to waste,” explains Barnes.

“It may be tempting to just serve it again at the next bottle feed, maybe even with some formula to make it go further, but once your baby has taken breastmilk from a particular bottle, that bottle needs to be discarded in two hours.”

That’s why the La Leche League International recommends doing separate feeds instead of mixing breast milk and formula in the same bottle.

If you have any other questions about feeding, know that you don’t have to struggle through this alone.

Check in with your healthcare provider.

They may refer you to a lactation specialist who will be able to help you.

And if you need support along the way, talk to your Peanut community.

We get it, and we’re here for you.