How to introduce a bottle to a breastfed baby

When to start

Most people introduce a bottle somewhere between three and six weeks: late enough that nursing is established, early enough that the baby is still relaxed about new things. If you have a date when a bottle will be necessary — returning to work, a trip, childcare — start at least two to three weeks before it, so a slow start does not become a crisis.

If you are unsure about timing for your own situation, a lactation consultant can advise on it in a way we cannot. What we can say is that leaving it to the last week is the version that reliably goes badly.

The method, step by step

1. Pick the moment. Slightly hungry, not ravenous, and not full. A calm, alert baby, not one at the end of a long day.
2. Have someone else offer it. If the nursing parent is in the room, the baby knows a familiar option exists nearby. Leaving the room genuinely helps.
3. Warm the milk to body temperature so it feels like what they are used to. Never in a microwave — see how to warm breast milk.
4. Use the slowest nipple flow. Fast flow is the most common reason a first attempt fails: milk arrives without the baby working for it, which is alarming rather than welcome.
5. Touch the nipple to their lips and wait. Let them open and take it rather than pushing it in. This is the same principle as a nursing latch.
6. Hold them upright with the bottle close to horizontal — paced bottle feeding. It lets them control the pace and it is the technique that makes switching between breast and bottle easiest. Full method in paced bottle feeding.
7. Stop if it becomes a fight. Five minutes of refusal is information, not failure. Try again at the next feed or the next day. Pushing turns reluctance into a learned aversion.

What to vary if the first attempt fails

Change one thing at a time, in roughly this order, because the cheap variables are also the most likely culprits:

1. Who is offering it. Free, and the most common fix.
2. Time of day. Some babies take a bottle happily at 10am and refuse it at 6pm.
3. Milk temperature. A little warmer, a little cooler.
4. Position. Facing out, upright, walking around, in a different room.
5. Nipple flow. Still the slowest, but check it is genuinely the slowest that brand sells — numbering is inconsistent between brands. See nipple flow sizes.
6. The bottle itself. Last, not first. A wider, softer nipple is the usual upgrade — the Comotomo is the bottle that most often works after others have failed. See best bottles for breastfed babies.

If you have been through all of that, the dedicated troubleshooting page is why won't my baby take a bottle?

Keeping it going once it works

The thing nobody warns you about: a baby who took a bottle at five weeks can refuse one at ten weeks if they have not had one in between. Offering a bottle once every few days keeps the skill alive and costs almost nothing.

If you are pumping to supply those bottles, storage matters. Per CDC guidance, freshly expressed milk keeps up to four hours at room temperature and four days in a fridge at 40°F, and leftover milk from a feed should be used within two hours. The table is in how long can breast milk sit out?