Combining Breastfeeding and Formula Feeding

Giving your baby formula in addition to breastfeeding is called supplementing. It's completely fine and perfectly safe to do.

Many families choose this type of combination feeding method, whether out of necessity (e.g. low breast milk supply), convenience, or simply personal choice. In some cases, breastfeeding and providing formula may be recommended by a doctor for medical reasons.

Reasons to Supplement Breast Milk With Formula
Verywell / Brianna Gilmartin

Reasons for Supplementing With Formula

The American Academy of Pediatrics (AAP) and the World Health Organization (WHO) recommend breastfeeding exclusively for the first four to six months and then continuing to breastfeed up until one year or longer, along with the introduction of solid food.

For this and other reasons, including emotions and cost, making the decision to supplement with formula may not be an easy one.

While many parents breastfeed their babies and give them formula because they want to, others do so because they have to. Regardless of whether all or none of these reasons for supplementing apply to you, the decision is entirely yours.

Your Child Has Medical Issues

If your baby was born prematurely or with certain medical conditions, they may need more than just breast milk. Supplementing is often done for the purpose of helping a baby gain weight.

You Have a Low Breast Milk Supply

A previous breast surgery or certain medical conditions can interfere with the production of breast milk, though any woman can experience low supply. If you or your doctor feel that your baby is not getting enough breast milk through breastfeeding alone, you may need to supplement with infant formula.

You're Going Back to Work

It may be too difficult or stressful to pump at work, or you may have a decrease in your breast milk supply once you return to work. If you don't have a stockpile of breast milk stored in the freezer, you may have to supplement your baby's diet with formula.

Your Partner Wants to Participate

Your partner may want to take part in feedings (and you might welcome sharing the responsibility). You could pump and use your breast milk, or you can give your little one a bottle of formula once in a while.

You Have Multiples

Exclusively breastfeeding twins or triplets can be a challenge. Not only do you have to build and maintain a large enough breast milk supply, but you'll be breastfeeding very often. You may just need a break a few times a day (both physically and mentally), and formula feedings can help with that.

You Just Want to

You may simply have a personal preference to breastfeed some of the time and give your baby formula the rest of the time.

When Doctors Recommend Supplementation

When possible, most doctors recommend exclusive breastfeeding. However, at certain times your physician may want you to supplement your breastfed baby with formula. This could include any of the following circumstances:

  • Fewer than six wet diapers in a 24-hour period
  • Fussiness and signs of hunger soon after feedings
  • Slow weight gain after the first few days
  • Weight loss of more than 10% of body weight in the first few days of life

Introducing Formula

If you're not supplementing your child for medical reasons, experts recommend breastfeeding for at least one month before starting formula. This gives you time to build up a healthy breast milk supply and ensure that your baby is breastfeeding well. At this point, you can slowly begin to add formula.

While it is OK to put breast milk and formula in the same bottle if you have already prepared the formula, mixing them can lead to wasted breast milk if your baby does not finish the bottle. If possible, give breast milk first, then finish the feeding with formula.

For safety reasons, you should never combine your breast milk with unmixed powdered or concentrated formula. Always prepare formula according to the manufacturer's directions, using clean water.

Before choosing an infant formula for your child, talk to your pediatrician. Most recommend an iron-fortified infant formula during the first year of life.

If your baby develops a rash, vomiting, diarrhea, excessive crying, fussiness, or gas after starting formula, it may be an allergy. Stop using the formula and check with the baby's doctor to discuss other infant formula options.

How Adding Formula Affects You

Supplementing will be a change if you've been exclusively breastfeeding. If possible, add formula gradually so that your body can adjust.

Start With One or Two Formula Bottles a Day

Each day, your body makes breast milk based on the concept of supply and demand. When you start to add formula, it can affect how much breast milk you make.

If you plan on supplementing one or two bottles a week, it shouldn't affect your breast milk supply. But if you give your child one or two bottles of formula a day, your milk supply will begin to drop.

Add More Formula Slowly

Going from not supplementing to giving a lot of bottles in a short period could cause problems such as breast engorgement and blocked milk ducts. It may also cause your child gastrointestinal issues.

Consider Pumping or Hand Expressing

Either practice can help maintain your breast milk supply and prevent some of the common breastfeeding problems that can pop up when you skip nursing to bottle feed. Removing your breast milk will help relieve the fullness that breast engorgement can cause.

Another benefit is that you can store your pumped breast milk to use at a later time. Depending on how you store it, breast milk can stay in the freezer for up to one year.

How Adding Formula Affects Your Baby

If you've been exclusively breastfeeding your baby and begin to add formula to their daily diet, there are some things you may start to notice. Usually, these are just part of the transition and your baby will eventually adjust to the new routine.

Refusing the Bottle

Your child may refuse to take the bottle, especially if you're the one giving it to them. The transition may go more smoothly if your partner or another caregiver offers the formula.

Aside from simply wanting milk from the breast, some babies may have a hard time getting the hang of using a bottle. Others may just not like the taste of the formula.

Waiting Longer Between Feedings

Since your baby can digest breast milk more easily than infant formula, the latter allows them to feel fuller longer. They may not seem hungry as quickly after formula feedings as they do after breastfeeding.

Refusing the Breast

Refusing the bottle is usually no longer an issue after some time. After your child gets used to the formula and drinking from a bottle, however, you may have the reverse issue: They may no longer want to nurse. Drinking from the breast takes more work, and many babies end up finding formula more satisfying.

Changes in Bowel Movements

Adding formula to your baby's diet may change the pattern, color, and consistency of your baby's poop (e.g., it may be firmer, darker in color, and have a stronger odor than before). Your child may also poop less often once you start giving them formula.

A Word From Verywell

The ultimate goal of every parent is to have a happy, healthy baby who is growing and thriving. It's great if you can breastfeed exclusively, but it's not always possible or desirable for every parent.

Breastfeeding doesn't have to be all or nothing. Every baby and situation is unique, and a combination of breastfeeding and formula may work best for your family.

6 Sources
Verywell Family uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. National Institute of Child Health and Human Development. What are the recommendations for breastfeeding?.

  2. Johns Hopkins Medicine. Managing poor weight gain in your breastfed infant.

  3. Nemours KidsHealth. Feeding your newborn.

  4. Nemours KidsHealth. Your newborn's growth.

  5. Nemours KidsHealth. Breastfeeding FAQs: Solids and supplementing.

  6. Centers for Disease Control and Prevention. Infant formula preparation and storage.

Additional Reading

By Donna Murray, RN, BSN
Donna Murray, RN, BSN has a Bachelor of Science in Nursing from Rutgers University and is a current member of Sigma Theta Tau, the Honor Society of Nursing.