Can You Mix Formula and Breast Milk?

By: Suzanne Renee' - updated December 18, 2023 - 7 Minute Read

Can You Mix Formula and Breast Milk? | The Milky Box

When it comes to breastfeeding, it does not have to be an all-or-nothing experience.

Combination feeding, using pumped milk for some meals and baby formula for others, affords you and your infant the fantastic health benefits of breastfeeding but offers an alternative when medical or everyday circumstances call for another nutritional option.

This article will discuss the safe way to mix breast milk and formula in the same bottle. It is essential to prepare it correctly. Here's how.

What Are the Advantages of Mixing Formula and Breast Milk?

Caregivers that struggle with low milk supply, breastfeeding more than one little one, or returning to work find combination feeding works well.

Other instances may include allowing a partner to share feedings or simply because it works best for the family.

Whatever your reason, the addition of baby formula can offer an option that meets nutritional needs while also allowing breastfeeding parents to address and adapt to daily life with a baby in tow.

Advantages of Mixing Breastmilk and Formula | The Milky Box

Can You Mix Breast Milk and Formula in the Same Bottle?

Breast milk can be fortified by adding powdered formula to it and giving the combination in a bottle. Following some guidelines will help make this process simple and safe. 

Prepare Formula First

Never add formula powder to breast milk or use breast milk instead of water to make the formula. The powdered formula must be mixed with water according to the manufacturer's directions in order to be safe for your infant.

Always follow the manufacturer's instructions to properly mix the powder and water. Maintain the right ratio of water to formula and then adding breast milk separately to ensure you won’t change the nutritional content of the formula. 

Adding excessive water to formula can dilute important vitamins and minerals, while insufficient water can strain a baby’s kidneys and digestive tract, causing dehydration and other health worries.

Add to Breastmilk

Once your powdered formula has properly mixed with water, it can add breast milk as needed. If you are using the ready-to-drink liquid formula, no extra steps need to be taken before combining it with your breast milk.

How to Mix Breast Milk with Formula Graphic | The Milky Box

What are the Risks of Mixing Formula and Breast Milk?

Infant formula is made to provide your baby with a specific number of calories and nutrients in a specific ratio to water. Adding powdered formula directly into your breast milk before diluting it with water changes the balance of nutrients and water in both your breast milk and the infant formula.

Health Concerns

When your baby is an infant, their kidneys are not yet mature. The kidneys of newborns and young infants need enough water to process all the nutrients in their feedings, especially the proteins and the salts.

When water ratios are incorrect, it can be dangerous and too much for new systems to handle. It is incredibly important when preparing your child's formula that you should always use the correct amount of water and follow the manufacturer's instructions as listed. 

For Safety and convenience, The Milky Box Lists Each European Baby Formulas Preparation and Nutritional Facts in English on The Individual Product Pages

European formula ingredients | The Milky Box

Breast Milk for One Feed and Then Formula for Another

You may find that combination feeding for your family is separate breast or bottle feeding.

Generally, when introducing formula to replace a breast, gradually replace breastfeeding sessions with formula feeding.

One proven method is to replace one nursing session per week with a formula feeding session. Start by giving your baby one bottle of formula at around the same time each day. This will train your body to stop producing milk at that time.

Protecting Your Milk Supply

Baby formula can be more filling and may cause your baby to take the breast less. Regular breastfeeding at least 8-12 times a day helps you keep a healthy milk supply, especially in the early weeks.

While combination feeding, there are a few tips that will help you keep a healthy milk supply:

🤱Pump or hand express at regular intervals to maintain or build your milk supply.

🤱You can also breastfeed on one breast while pumping on the other.

🤱Do not start combination feeding until you are breastfeeding regularly and well.

🤱If possible, return to work part-time for a week or two before going full-time.

🤱Look for childcare close to work so that you may be able to breastfeed your baby during a break, and your caregiver can offer formula while you are away.

Protecting your breastmilk supply | The Milky Box

Ensure Safe Storage and Disposal of Breast Milk and Formula

The composition of breastmilk and baby formula are not the same. The rules for the storage, use, and disposal of each vary. 

Breast Milk

The gold stand of nutrition can be frozen in a food-grade plastic container or breast milk storage bags for 6 months.

Once thawed, it can stay fresh in the refrigerator for up to 24 hours.

Freshly pumped breast milk can be kept in the back of the refrigerator for up to 5 days or in an insulated cooler, if you are on the go, for up to 24 hours.

After 2 hours, leftover breast milk should be thrown away. To avoid wasting unfed milk, consider storing, thawing, and warming milk in smaller amounts.

Baby Formula

Bacteria reproduce quickly in cow milk, goat milk or vegan-based formulas, so all baby bottles of formula should be used within an hour. Never try to save a partially used prepared formula.

Please do not store baby formula in powdered form or premixed inside a refrigerator or freezer.

Condensation will lead to mold and bacteria growth that is extremely harmful to your baby, and freezers can negatively affect all baby formula’s components and overall nutritional value.

Breastmilk and Baby Formula Mixed

Once you have combined your premade baby formula with breast milk, the same rules for formula storage will apply. Room temperature bottles should be discarded after 1 hour from the start of use.

safe storage and disposal | The Milky Box

Will Formula Make My Breastfed Baby Sick?

Choosing an Infant formula that is specially designed to mimic breast milk and provide all the proper nutrients your baby needs to grow and thrive is essential.

When combined with breastmilk, families are choosing European formulas due to the highest quality ingredients and certified farms that consider the entire ecosystem. Parents will never find soy, non-lactose sugars, toxic ingredients, or genetic modifications in any part of the process from farm to bottle.

European formulas are full of pure and simple ingredients that start with 100% grass-fed milk and end with a formula as close to breast milk as possible.

Considerations When Mixing Milk in the Same Bottle

Breast milk and baby formula can be the perfect combination when looking for nutrition that sets a firm foundation for a lifetime of health.

The Milky Box offers European baby formulas that will give you peace of mind and comfort, knowing that you are giving your baby nutrition that mimics breast milk as closely as possible.

Clean, pure ingredients that support healthy growth and development without unwanted or toxic ingredients from day one

Frequently Asked Questions

How to mix breast milk and formula together?

Whether you're making formula from powder or concentrate, always prepare it in a separate container according to the manufacturer's directions first and then add in pumped breast milk.

A ready-to-serve formula can simply be combined with expressed milk.

Is it safe?

If you're wondering if you can mix breast milk and formula in the same bottle, the answer is yes!

Does formula taste the same as breast milk?

The best infant milk formulas are designed to match the taste and nutrition of breastmilk. Choosing European formulas will get families as close as possible. 


Please be aware that this information is based on general trends in babies, and it is not medical advice. Your doctor should be your first source of information and advice when considering any changes to your child’s formula and when choosing your child’s formula. Always consult your pediatrician before making any decisions about your child’s diet or if you notice any changes in your child.

Breastfeeding is the best nutrition for your baby because breast milk provides your child with all the essential nutrients they need for growth and development. Please consult your pediatrician if your child requires supplemental feeding.

Suzanne Renee' is an accomplished professional with extensive expertise in the area of infant nutrition, dedicated to promoting the health and wellbeing of children. She started this journey as a foster parent. Suzanne has emerged as a strong proponent of the European baby formula and has become a full time writer of the subject. In her free time, she enjoys camping, hiking and going to church.

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Reviewed by Dr. Eric Wood, ND, MA

Dr. Wood is a licensed naturopathic doctor, with a doctorate degree from the Canadian College of Naturopathic Medicine in Toronto, Canada. He received his post-graduation certification in Mind Body Medicine at Harvard University.

With 15 years of experience, Dr. Wood is an Associate Professor of Holistic Nutrition at the American College of Health Sciences in Portland, Oregon. Dr. Wood is an educator, clinician, author, media figure, consultant, and owns his own holistic (naturopathic) medical practice in Ft. Lauderdale, Florida. Dr. Wood is currently researching and drafting books on cancer and pediatrics.

Outside of the medical profession, Dr. Wood loves singing with the Miami Lyric Opera and is an avid musician in South Florida. He also loves spending time with his wife and kids.