A lot of parents ask how me long a bottle can sit out before it goes bad, especially if their baby takes small amounts at a time.
The answer? It depends. There are several factors that determine how long you can safely feed your baby a bottle of breast milk or baby formula. These include how it was prepared, temperature, prep area cleanliness and whether your baby has already fed from it, for example. Here's what you need to know.
How to safely prepare your baby's bottle
How you store and prepare baby’s food have a big impact on its quality and safety. Follow these science-backed tips when preparing your baby's bottles. Note: If your baby was born prematurely or has other health conditions, reach out to your pediatrician for additional guidance.
Make a clean start. Before preparing formula or expressing breast milk, wash your hands with soap and water or use hand sanitizer that contains at least 60% alcohol. Be sure to clean the area you'll use to mix formula, using sanitizing wipes or hot water and antibacterial soap. Bottles, bottle parts and storage containers should be pre-sanitized and ready to go.
If you're pumping, inspect your pump and supplies. Make sure that all valves, tubing and flanges are clean and in good condition. Use only sanitized, food-grade bags and containers to store expressed milk.
Label everything. Bags and bottles should show the date and time you expressed the milk or mixed the formula. If your baby attends child care, add their name to bottles and containers too. Ask your child care provider about specific guidelines for breast milk storage and administration.
Consider making smaller batches. This helps reduce waste if your baby doesn't drink the whole bottle, since leftover milk should always be discarded after one hour. You'll dump less out if you prepare and use 2-ounce to 4-ounce batches of formula. Consider freezing breast milk in these smaller amounts too, so it's easy to thaw them as you need them.
Keep prepared bottles in the back of the fridge. Although it might seem more convenient to stash them in the door, remember that every time you reach for something, warm air rushes in. The temperature stays more consistent toward the back.
Do not put infant cereal or other foods in your baby's bottle. Contrary to what you may have heard, thickening your baby's milk or formula will not help them feel fuller or sleep longer. Worse yet, it increases the risk that your baby will choke. Breast milk and formula on their own will provide all the nutrition and hydration your baby needs to feel full and relaxed.
So, how long can bottles sit out safely?
Once you finish feeding your baby, any prepared infant formula left in the bottle should be thrown out within 1 hour. Pre-mixed formula or breast milk stored in clean bottles can be kept longer, depending on the temperature and location.
Here are guidelines for safely storing everything from fresh breast milk to powdered formula supplies:
Type of Breast Milk or Formula
Place and Temperature
Countertop (77ᵒ F or cooler)
Refrigerator (40ᵒ F or cooler)
Freezer (0ᵒ F or cooler)
REMEMBER: After feeding baby, toss out any milk left in the bottle within 1 hour.
Freshly expressed or pumped breast milk
Up to 4 hours
Up to 4 days
Up to 9 months (use within 6 months for best quality)
Fresh breast milk stored in the fridge is good for 4 days, but DON'T freeze it if you don't use it in that time frame. Toss it out.
If you don't think you will use freshly expressed milk within 4 days, freeze it right after pumping.
Thawed breast milk from freezer
Up to 2 hours
Up to 24 hours
Do not refreeze
Because breast milk expands as it freezes, remember not to fill your storage containers all the way to the top.
Label all breast milk containers with the date the milk was expressed.
Thaw and use the oldest breast milk first (think: first in, first out).
To prevent burns, NEVER use a microwave or stovetop to thaw or warm breast milk. Set bags or containers on a clean countertop to thaw at room temperature.
To warm a refrigerated bottle before feeding, hold it under a stream of warm tap water or place in a bowl of heated water for a few minutes. Shake well to eliminate "hot spots."
Prepared infant formula
Up to 2 hours after preparing (1 hour if your baby has already started feeding)
Up to 24 hours
Do not freeze
Use only water from a safe source to prepare formula.
Always follow the instructions on the package. NEVER stretch formula by adding more water. This deprives your baby of nutrients they need to grow.
Always measure the water first, then add powder or concentrate and shake well.
To prevent burns, NEVER heat prepared formula in a microwave or on the stove. Bottles can be warmed by holding them under a stream of warm tap water or placing them in a bowl of heated water for a few minutes. Shake well to eliminate "hot spots."
Formula powder or concentrate
Check label instructions.
Mark containers with the date and time they were opened.
Do not refrigerate powder.
Refrigerate liquid concentrate after opening. Use within 48 hours of opening.
Do not freeze.
Store unopened containers of formula in a cool, dry place.
Keep any opened canister of powdered formula tightly capped.
Never use formula after the "Use By" date on the label.
As parents, we all want to give our babies the best nutrition to help support their growth and development. If you have any concerns or questions, or if your baby was born pre-term or has special health conditions, reach out to your pediatrician for more guidance.