Can You Mix Formula and Breast Milk?

Mixing breast milk and formula is acceptable, although it's generally not the preferred choice. Human milk is a valuable bioactive material with many functions, not only nutritional.

baby drinking from a bottle
Baby drinking from a bottle.

You may have some concerns about mixed feeding. But rest assured, if your baby is breastfeeding regularly and there are no medical reasons, then you don't need to supplement with formula. Your breast milk should be enough! However, there may be situations where mixed feeding is a great solution, like if you have a low milk supply and still want to continue breastfeeding. Before doing mixed feedings, read  - signs that my baby is getting enough milk. Now, let's explore how to give your little one a mix of breast milk and formula in those special circumstances.

Can You Mix Formula and Breast Milk?

Mixing breast milk and formula is acceptable, although it's generally not the preferred choice. Human milk is a valuable bioactive material with many functions, not only nutritional. Therefore, it is worth giving it to the baby first. Mixing it with baby formula exposes it to the loss of some properties and to quantitative losses (the baby does not consume the whole portion, etc.).

Another consideration is the different storage times and shelf lives of these two types of milk. Formula can harbor harmful bacteria, and since it's made from cow's milk that undergoes chemical processing, there's a higher risk of contamination during production and use. Additionally, prepared formula can be a breeding ground for bacteria and other microorganisms.

The way baby formula is prepared is crucial for both its quality and your baby's safety. Per safety guidelines, prepared formula stored at room temperature must be used within an hour and discarded afterward. On the other hand, breast milk can be stored at room temperature for up to 4 hours. This is why it's best to first feed your baby with breast milk and then supplement with formula if needed.

Some moms may be tempted to thicken their milk with formula to increase its calorie content. However, this is not recommended as it can alter the composition of breast milk. Additionally, the ingredients in formula become much more concentrated, which can be harmful to your baby's developing kidneys.

It's important to always follow the instructions on the formula packaging, as each product has different recommended proportions. Make sure to only mix the powder with properly prepared water.

Important! Never use breast milk instead of water to prepare baby formula.
Two baby bottles, milk bottle, baby bottle
Two baby bottles - Photo by Jaye Haych / Unsplash

Pros and Cons of Mixed Feeding

The main advantages of mixed feeding are relief (especially at night), the ability to return to work, and convenience. As for the disadvantages — breast milk will always be better for your baby than even the best formula.

Before you make any decision, talk to your doctor, midwife, or your baby's pediatrician. Specialists will answer all your questions and help you choose the best solution for you and your little one.

Are Mixed Feedings Safe for Newborns?

Yes, but it's best to let your baby get the hang of breastfeeding in the early days and weeks after birth. While mixed feeding has the same purpose, sucking milk from a bottle requires different muscle coordination in the tongue, jaw, and throat compared to breastfeeding.

Mixing feeding and breastfeeding can sometimes impact a baby's ability to learn how to effectively suck at the breast. It takes around 30-60 seconds for the baby to get the milk flowing from the breast, so if they haven't learned this technique and start receiving formula right away, they may not be interested in breastfeeding. If you're hoping to breastfeed, wait until at least six weeks after birth before introducing a bottle to give your baby time to establish a proper suckling technique.

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Alternative Feeding Methods

Is there any alternative to bottle feeding for a baby? Yes, it's worth exploring other options to prevent your baby from becoming too accustomed to a bottle. You can try feeding your baby using a spoon, special feeding cup, dropper, or a syringe without a needle.

Using an SNS can be advised for mothers with a low milk supply because it allows them to continue breastfeeding their baby while supplementing with formula or breast milk through the feeding tube attached to a bottle. This system provides the baby with the necessary nutrients and allows the mother to stimulate lactation and increase her milk supply through the act of breastfeeding. It also offers the benefits of bonding and stimulation of jaw development for the baby, as well as nipple stimulation for the mother. By using an SNS, the baby can still receive the benefits of breast milk and the mother can continue to enjoy the experience of breastfeeding.

If these alternative methods don't work, bottle feeding is still an option. In this case, it is always best to try paced bottle feeding methods.

Paced Bottle Feeding

Paced bottle feeding is a method of bottle feeding that mimics the natural pace of breastfeeding and prevents overfeeding. In this method, the baby is fed in an upright position, and the bottle is held horizontally, tilted only enough to fill the teat halfway with milk. The baby is encouraged to latch onto the nipple without forcing the nipple into their mouth, and the feeding is done according to hunger cues, not on a schedule. The baby should be fed no longer than when breastfeeding and with frequent pauses, just as they would when breastfeeding. During feedings, the baby should be burped often while switching sides, and the amount of milk expressed or formula given should last for the duration of a typical breastfeeding session. The benefits of paced bottle feeding include providing the baby with the right amount of milk for their age and size, promoting breastfeeding, and reducing colic symptoms.

Is It Possible to Maintain Lactation With Mixed Feedings?

Yes, it is possible to maintain lactation. Although, a mother needs to remember that breastfeeding and expressing milk stimulates milk production, so if the baby is not nursing, the mother's milk supply will eventually decrease. If a mother wishes to continue breastfeeding, it's important to maintain a regular nursing schedule and to pump if necessary to keep her milk supply up. Additionally, supplementing with formula can reduce the demand for the mother's milk, which can also lead to a decrease in milk supply.

nursing, breastfeeding, mixed feeds
Mother breastfeeding her baby

Switching from Mixed Feeds to Exclusive Breastfeeding

If you're interested in switching from mixed feeding to exclusively breastfeeding, it can take some time and effort, but it is possible. Some factors that can affect the process include the frequency of breastfeeding and pumping and the gradual reduction of formula use. It's important to continue putting your baby to the breast or pump regularly to help maintain lactation. You can also try to gradually reduce the amount of formula you're giving your baby until you are exclusively breastfeeding. Remember to be patient and kind to yourself as you work towards your goal.


Breast milk is considered the best nutrition for a baby, and it's recommended to breastfeed as much as possible. Mixing breast milk with formula is acceptable in certain circumstances, such as if a mother has a low milk supply or is returning to work and wants to continue breastfeeding. However, it's important to note that formula is not equivalent to breast milk and can contain harmful bacteria if not prepared and stored properly.

Mixing formula with breast milk should be done carefully by following instructions on the formula packaging and adding breast milk to already prepared formula. Mixing breast milk and formula can result in the loss of some of the properties of breast milk, and it's not recommended to thicken breast milk with formula.

Mixed feeding can also impact a baby's ability to learn proper breastfeeding techniques, and it's important to talk to a doctor or midwife before making any decisions about feeding. Maintaining lactation with mixed feedings is possible, but it requires a regular nursing schedule and pumping if necessary.

If a mother wishes to switch to exclusively breastfeeding, it can take time and effort, but it is possible by gradually reducing formula use and maintaining a regular breastfeeding schedule.

It's important to seek professional advice and make informed decisions about feeding based on individual circumstances.