Introducing Infant Formula to a Breastfed Baby


Read time: 7 minutes

What should I know about switching partially or fully to formula

  • When formula feeding may be beneficial

  • How much formula does your little one need?

  • How to supplement with formula

  • How to switch fully to formula from breastmilk

  • Tips on how to introduce a bottle to a breastfed baby

We always want to do what is best for our babies, and sometimes that means introducing formula to make sure you and your baby are happy and healthy.

When introducing formula or transitioning from breastmilk to formula, you might feel upset or guilty about changing your breastfeeding relationship with your baby or ending it earlier than planned. You may also feel relieved. All of these emotions are normal. Rest assured that a fed baby is what matters most.

Reasons formula may be introduced

There are plenty of situations in which supplementing with formula or switching from breastmilk to formula makes sense. Whether out of medical necessity or by choice, you will continue to support your baby's growth and sustain a nurturing relationship when transitioning partially or fully to formula.

Here are some situations where supplementing with formula or switching from breastmilk to formula may be suggested:

  • Prolonged separation (when pumping to provide expressed breast milk isn’t an option, such as due to maternal illness)

  • Mom must take a medication that will cross into the milk and isn’t safe for baby1

  • Baby has an inborn error of metabolism (e.g. galactosemia, a rare genetic disorder where infants are unable to metabolize the sugar in human milk or standard cow’s milk based formula)2

  • Baby’s ability to feed at the breast is compromised for physiologic or developmental reasons.3,4,5

  • Mom has a delayed milk production or has a low milk supply6,7,8,9

  • Mom has had a prior breast surgery or an innate breast physiology resulting in poor milk production.10

  • Mom has intolerable pain during feedings which could not be relieved by interventions.11,12,13

  • Breastfeeding causes too much anxiety or other negative emotions.18,19

Chat with a Happy Expert to help you explore your options. Reach out to our team of registered dietitian nutritionists and lactation consultant for free! They’re here to help on our free live chat from Monday - Friday, 8am-6pm (ET). Chat Now!

Should I feed formula on a schedule or feed as often as I would normally breastfeed?

When bottle feeding a breastfed baby, the initial formula feeding pattern will mimic your breastfeeding pattern. For example, if you usually breastfeed 8 times per day, continue to offer formula that often. Listen to your little one’s hunger and fullness cues to know when they are ready to eat, and when they are ready to stop feeding from the bottle.14,15

If you are taking out just one or a few breastfeeding sessions, such as if you are going back to work and are choosing not to pump, or do not have enough pumped milk available, offer a formula bottle for each breastfeeding session skipped.

Read more:

Should I Formula Feed On Demand or on a Schedule?

Understanding your Baby’s Hunger and Fullness Cues

How much formula does my baby need?

Generally, a breastfed baby will take about 3 to 5 ounces each feeding, so you can start with that amount of formula per bottle.16 Provide more or less depending on your little one’s hunger and fullness signs. Try not to make your baby finish a bottle if they are showing signs that they are satisfied.15

If you are transitioning fully to formula, eventually your little one may begin taking more ounces per bottle and eating less frequently.17 Follow their lead to know when they are ready for this transition.

Using paced bottle feeding can help with knowing when your baby is full. This type of responsive feeding will help you know you are giving your little one the right amount of formula.

Learn more:

What is Paced Bottle Feeding?

How Much Formula Does My Baby Need?

Everything You Need to Know About Preparing and Storing Infant Formula

Tips for introducing formula or switching from breastfeeding to formula

Some babies become gassier on formula

When introducing a bottle and/or formula, many babies may become temporarily a bit gassier. This can be normal.

Formula may cause gas if a lot of bubbles or foam formed when shaking the powder and water together.20 This may allow baby to swallow more air. Let the bottle sit in the fridge until all bubbles have dispersed.

Good news: Most formulas can be prepared up to 24 hours in advance and kept in individual bottles in the refrigerator, allowing for plenty of time for the bubbles to reduce.

Incorrect bottle feeding and latch may also cause baby to swallow more air, which results in more gas.21 Used paced bottle feeding to help with this.

Be aware: Some babies may have a food intolerance or allergy to an ingredient in the formula. If you also notice changes in baby’s stool, such as mucous or blood; forceful vomiting; or excessive crying or fussiness after a feeding, chat with baby’s pediatrician about this possibility.22

Read more: How Do I Relieve Gas in my Formula or Bottle-Fed Baby?

Get ready for changes in stool color

Formula often causes stool to be a green, brown, or darker yellow color.30 These changes are usually normal.

Some babies refuse the bottle

Your little one knows what they like and what they are familiar with, and often that’s you! Moving to a latex nipple can be quite the adjustment for some babies.

Here are some tips to help your baby take a bottle

  • Start trying out the bottle about a month or so before you know it must be used.

  • Begin offering the bottle when your little one is the most calm, alert, and happy.

  • Have someone else offer the bottle in a quiet room away from mom.

  • Feed when baby is a little hungry, but not so overly hungry that they have no patience for learning how to drink from a bottle. This is usually about 1 to 2 hours after their last feed.

  • Use paced bottle feeding, allowing baby to suck the nipple into their mouth on their own (don’t force it in). This will also allow baby to pace the feed more similarly to a breastfeeding session.

  • Try walking around while feeding baby.

  • Offer the bottle every day, even multiple times per day.

  • Stop the bottle attempt if your little one gets too frustrated or if baby has not fed for 10 minutes.23,24

If your baby is refusing the bottle for a few days, try a different bottle and/or nipple.

Still refusing the bottle after a few weeks? Try an alternate feeding method

For a younger infants, a small flexible cup (such as a medicine cup or a soft infant cup feeder), syringe, or spoon may be used.23,25 These feeding methods require specific techniques, so call baby’s pediatrician before trying and consider meeting with a lactation consultant for personalized guidance.

For older infants try a slightly larger flexible cup (such as an infant or toddler training cup) or a sippy cup.27 By 6 months, littles ones are ready to learn to drink from a cup, so this transition may be a bit easier.29

Know that most little ones will begin to accept the bottle over time and with consistent introduction.

If your little one is refusing the bottle and you want to try one of the above methods, reach out to our team of registered dietitian nutritionists and lactation consultants, chat here!

Call baby’s pediatrician before making a switch to these methods.

Are you concerned about low milk supply?

Sometimes moms of fussy babies become nervous and assume they are not making enough milk and feel they should add formula. But milk production is a supply and demand relationship: you have to empty your breast in order for it to make more.31

By giving baby a bottle instead of putting them to your breast or pumping, you may be jeopardizing your milk supply.

If you are considering switching from breastmilk to formula because you are concerned that your supply is too low, or because breastfeeding is painful or challenging, consider contacting a lactation consultant first. A lactation consultant can help you assess your milk supply as well as baby’s latch.

Read more: Dealing with a Low Milk Supply

Consider combination / mixed feeding

Breastfeeding is not all or nothing. Your baby will reap the benefits of breast milk for whatever duration you provide it, and in whatever quantity.33 If there is no medical indication to stop breastfeeding, you may want to breastfeed for one or two feedings (or more) and offer formula the remainder of the day.

Choose a time of day that feels right to you. Many moms breastfeed at night or first thing in the morning when the milk supply is highest.

This lets the baby continue to receive breast milk’s immune properties and growth factors. Most women will continue to produce enough milk for breast feeding sessions while also down-regulating supply for when formula is provided instead.35

But be sure to monitoring weight gain and diaper output to ensure your little one continues getting enough.32

Read more: How do I Supplement my Breastfed Baby with Formula?

Pump if you want to go back to breastfeeding in the future

If your need for formula feeding is temporary (due to a medication you must take, for example), it’s important to pump to maintain your supply. This allows you to go back to nursing when it is safe to do so.

Pump as many times as baby takes a bottle of formula to let your body know your baby still needs that much milk.32 Dump this milk if you must or freeze it if the milk is safe for your baby to drink later.

Read more:

How to Choose the Right Breast Pump

Top Tips for Pumping Breastmilk

Wean from the breast slowly

Weaning too quickly may lead to engorgement, clogged ducts, and even mastitis. If possible, wean over several weeks, taking out only one to two breastfeeding sessions every few days and replacing them with formula.33

Your body will slowly reduce your breastmilk supply.

If you feel uncomfortable and engorged between feedings or pumping sessions:

  • Hand express a very small amount to help you feel more comfortable

  • Apply ice to help reduce swelling

  • Place clean cabbage leaves between the breast and the bra, replacing them when wilted

  • Massage the breasts

  • Wear a firm but non-binding bra for support.33,34

Read more:

How and When to Hand Express

Preparing to Wean your Child

Let's Chat!

We know parenting often means sleepless nights, stressful days, and countless questions and confusion, and we want to support you in your feeding journey and beyond.

Our Happy Experts are a team of lactation consultants and registered dietitian nutritionists certified in infant and maternal nutrition – and they’re all moms, too! They’re here to offer personalized support on our free, one-on-one, live chat platform Monday - Friday 8am-6pm (ET). No appointment needed, no email or sign-up required. Chat Now!

Read more about the experts that help write our content!

For more on this topic, check out the following articles:

Transitioning to Cups for Babies and Toddlers

How Much Formula Does My Baby Need?

Choosing the Best Bottles and Nipples for your Baby

Does your Baby Need a Sensitive Formula?