If you’re a parent, you may find yourself asking the big question – can I mix breastmilk and formula?

With all of the conflicting information out there and the overwhelming amount of pressure to give your baby the best nutrition possible, it can be difficult to navigate this topic.

Fortunately, we’ve done all of the research for you! In this blog post, we will break down not only why it is safe (or not!) to mix breastmilk and formula but also provide clear-cut dos and don'ts so that you have all of your burning questions answered!

Join us as we explore whether or not mixing breastmilk and formula makes sense for your family.

Can you mix breastmilk and formula?

Quick Answer - Yes you can mix them, but for how, when and what to do, read on!

Reasons to mix breastmilk and formula

For parents wanting to get the benefits of both breast milk and baby formula, mixing them together can be an attractive option. This is known as combination feeding. After all, why not get the best of both worlds?

Some mothers may wish to do so as they aren't making enough breastmilk, and the formula can act as a top up.

Or maybe you want to try and return to work and the thought of expressing in the office isn't an option. Check out our article on the best breast pumps for working moms.

Maybe you are traveling and formula may be an easier solution half the time, or dad may want to feel a little more involved.

Some say that babies sleep for longer periods with breast milk as it takes longer for them to digest this.

Whatever your reason, it's your decision and of course, always talk to your doctor about any questions or concerns.

Making baby formula bottles

How to mix breast milk and formula

Understanding the facts surrounding the mixing of breast milk and formula can make a significant difference in your baby's health.

Formula Chaser

One way is to give the breastmilk first, then followed by additional formula (if necessary) in a separate bottle, to act as a top up if the baby is still hungry.

A mixed bottle

Another way is to mix the breast milk and formula in the same bottle. If doing so the formula should be prepared first as per the instructions, then add the breastmilk. Make sure they are mixed well together before serving.

Note that when learning how much formula to use, the methods differ depending on if you use powdered or concentrated formula.

Do's & Don'ts when mixing breastmilk and formula

✓ When it comes to the delicate balance of mixing breastmilk and formula, it helps to start with a light touch - literally! While both can be beneficial for babies, it's important to proceed cautiously when introducing new liquids into your child's diet.

✓Always make sure that both are sterile and served at a safe temperature before they are consumed.

✓If giving separately when possible put the mixture in unique bottles so there won't be any confusion between which bottle contains pure formula or breastmilk. A little bit of caution and care can go a long way in ensuring that the mix remains healthy and pleasant for your baby.

✘Never store already prepared bottles with both milk types as this can lead to bacterial contamination.

✘Don't ever use breast milk instead of water to prepare the formula.

Never store a bottle with the nipple on in the fridge or freezer.

Don't store bottles with nipples on

How to properly store breastmilk and formula

Preparing pre-mixed formula and breastmilk can be a great way to ensure your child gets all the nutrition they need on busy days, but it is important to remember to properly store pre-mixed bottles before using them.

You can store milk in special BPA free bags or handy storage bottles.


Breastmilk can be stored in the fridge for 4 days and up to 6 months in the freezer. Freshly pumped breast milk at room temperature it's fine for up to 5 hours.


A good rule of thumb is that any pre-mixed formula must be used within 24 hours if in the fridge. For best results, keep the bottle at or below 40°F throughout storage, as this will help keep bacteria and contaminants away.

But a bottle that has been used must be thrown away if not consumed within 1 hour from when the feeding started.

When it comes time to feed your child, warm the bottle up in a bowl of warm water versus microwaving it—this keeps the nutritional value high!

Remember: Pre-mixing formula and breastmilk might look easier on the surface, but if done incorrectly can cause health issues for your baby, so always err on the side of caution!

Breastmilk storage options 

Risks of mixing breast milk and formula

If you introduce formula then be prepared for your milk supply to start to reduce. If you aren't using its full capacity then it can start to trail off.

You may find that you are wasting breast milk. If you mix the two in a bottle and your baby doesn't drink it within the hour, it has to be thrown away. So it's best to try and weigh up how much they want and need. Maybe give breast milk when you know they are hungry.

Depending on the formula you choose, some children have allergies to certain kinds of products, especially cow's milk. But you won't know until you try, and there are lots of options out there.

Cows milk is much more susceptible to bacteria when storing, so follow the storage guidelines closely.

Tips for combining breastmilk and formula for a baby who is transitioning from one to the other

Combining breastmilk and formula when transitioning your baby from one to the other can be a difficult decision. Thankfully, there are some tips you can follow to make sure that your baby is getting all of the nutrition they need at this important stage in their life.

Firstly, it's important to introduce formula gradually as this will help build up your baby's tolerance.

Secondly, avoid mixing large quantities of breastmilk and formula together as this could create an imbalance of nutrients.

Finally, if you do mix breastmilk with formula, always ensure you shake the bottle or cup thoroughly to combine them properly! With these tips in mind, you can rest assured that your little one is getting all the essential vitamins and minerals for healthy growth.

To mix or not to mix?

All in all, it can be hard to keep up with the ever-evolving opinions and recommendations regarding mixing breastmilk and formula. For an experts opinion, a good baby book can be a great source of knowledge too.

Luckily, though, with the right approach and knowledge of some key facts you can make sure your little one is getting all the nutrients they need. Taking time to understand the pros and cons of combining formula and breastmilk, getting tips from a doctor about what's best for your baby’s nutrition needs, as well as being aware of how to properly store pre-mixed solutions can help ensure that your bundle of joy has enough nourishment during this crucial developmental period.

Though this may sound intimidating at first, it can be managed with a bit of preparation and research – resulting in both you and your baby feeling secure knowing your little one is receiving the best nutrition possible.

And, if you'd like some more help choosing the right containers to store your milk, we've found the best breast milk bags and even bottles that can be used to pump, store and feed, saving you valuable time.

Mixing breast milk and formula FAQS

In case we haven't covered everything already, here are some frequently asked questions on the topic.

What's better formula feeding or breastfeeding for the mother?

A breastfed baby has many benefits that go beyond just the nutrients, they can build a strong bond with the mother. But this can also be very tying and exhausting on just one parent if they are exclusive breastfeeding.

At what age can I start combining breast milk and formula?

This is different for every child and circumstance, but most doctors recommend waiting until baby is at least 3 months old before introducing formula, as breast milk provides important nutrition during their first few months of life.

What are the benefits of combining feeding methods?

Combining feeding methods has a lot of advantages, such as reducing pressure on mothers who may not have enough stored up milk or need to supplement due to medical reasons. It also gives parents more flexibility in scheduling feedings, whether it’s during working hours or out-of-town trips.

What's the difference between powdered formula and concentrated liquid formula?

The biggest difference between powdered and concentrated liquid baby formula is their respective shelf lives. Powdered formula typically has a much longer shelf life. Additionally, powdered formula is much more cost effective than concentrated liquid, as it typically comes in larger containers that can be used to make multiple batches of formula.

Another difference between the two types of baby formulas is the preparation process. Powdered formula must be mixed with water and heated before being fed to your baby. Some ready to use liquid formulas, on the other hand, require no mixing and are ready to feed once it has been opened.

What is the best baby formula brand?

The best powdered infant formula brand will vary depending on a child's individual needs. Most pediatricians recommend trying several brands of formula until you find one that works well for your baby.

How do I prepare powdered infant formula?

Powdered infant formulas require thorough preparation to ensure safety and proper nutrition for babies. To make sure it’s safe, mix the powder with previously boiled water according to the instructions on the label and cool it down before feeding your baby.

Can I give my newborn cow's milk?

No, cow’s milk should not be given as a substitute for breastmilk or infant formula during the first year of life because it doesn't contain enough iron and other essential nutrients that infants need in their early months.

Best breastfeeding books

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