Infant formula: 7 steps to prepare it safely
You've chosen your baby's infant formula with care — but are you preparing it properly? Follow these steps to ensure proper nutrition and avoid food-related illness.
Medically reviewed on Aug 24, 2018
1. Check the expiration date
Look for an expiration or "use by" date on the formula container. If the expiration date has passed, you can't be sure of the formula's quality. Don't buy or use outdated infant formula.
2. Wash your hands
Before preparing formula, wash your hands thoroughly with soap and water. Dry your hands well.
3. Prepare your bottle
Sterilize bottles, nipples, caps and rings before using them for the first time. You can boil the bottle and accessories in water for five minutes, use a microwave steam sterilizer bag or use a stand-alone electric steam sterilizer.
After the first use, there's no need to sterilize your bottle and accessories. Wash these items with soap and water and allow them to air-dry. Bottle and nipple brushes can help you clean nooks and crannies. You can also use a dishwasher.
4. Add water to liquid-concentrate or powdered formula
If you're using liquid-concentrate or powdered formula, you'll need to add water. Follow the manufacturer's instructions for how much water to use.
You can use any type of clean water — tap or bottled — to prepare liquid-concentrate or powdered formula. If you use well water or you're concerned about the purity of your water supply, talk to your baby's doctor or the water department. Well water needs regular testing. To kill bacteria that might be present in municipal water, use tap water that has been boiled for one minute and cooled quickly to body temperature, 98.6 F (37 C). Then, mix the water with formula.
It's also important to consider the amount of fluoride in the water you use to prepare your baby's liquid-concentrate or powdered formula. Exposure to fluoride during infancy helps prevent tooth decay during infancy. However, regularly mixing powdered or liquid concentrate formula with fluoridated water might increase your child's risk of developing faint white lines or streaks on the teeth (fluorosis) if these kinds of formula are your child's main source of food.
If you're concerned about fluorosis, consider ways to minimize your baby's exposure to fluoride. For example, you might use ready-to-feed formula, which contains little fluoride, or alternate between using fluoridated tap water and low-fluoride bottled water — such as purified, demineralized, deionized or distilled bottled water — to prepare concentrated formula. However, if you feed your baby only ready-to-feed formula or concentrated formula mixed with low-fluoride water, your baby's doctor might recommend fluoride supplements beginning at 6 months.
5. Measure the formula
For ready-to-use formula:
- Shake the formula well.
- Pour enough formula for one feeding into a clean bottle.
- Use only formula — don't add water or any other liquid.
- Attach the nipple and cap.
For liquid-concentrate formula:
- Shake the concentrated liquid before mixing it with water.
- Pour the amount of formula for one serving into the bottle, which already contains the appropriate amount of water.
- Attach the nipple and cap and shake well.
For powdered formula:
- Determine the amount of formula you want to prepare, following instructions on the package.
- Use a measuring cup to measure the amount of water needed and add the water to the bottle.
- Use the scoop that came with the formula container. Fill the scoop with powdered formula. Add the number of scoops needed.
- Pour the scoop or scoops into the bottle.
- Attach the nipple and cap and shake well.
6. Warm the formula, if needed
It's fine to give your baby room temperature or even cold formula. If your baby prefers warm formula place a filled bottle in a bowl of warm water and let it stand for a few minutes — or warm the bottle under running water. The formula should feel lukewarm — not hot.
Don't warm bottles in the microwave. The formula might heat unevenly, creating hot spots that could burn your baby's mouth.
Discard remaining formula at the end of each feeding if it has been more than an hour from the start of a feeding. Resist the urge to refrigerate a bottle once you have fed your baby from it, since bacteria from your baby's mouth can still multiply in the refrigerator.
7. Store formula safely
If you're using ready-to-use formula, cover and refrigerate any unused formula from a freshly opened container. Discard any leftover formula that's been in the refrigerator more than 48 hours.
If you prepare and fill several bottles of liquid-concentrate or powdered formula at once:
- Label each bottle with the date that the formula was prepared.
- Refrigerate the extra bottles until you need them.
- Discard any prepared formula that's been in the refrigerator more than 24 hours.
If you're unsure whether a particular container or bottle of formula is safe, throw it out. Don't freeze formula, which can cause the product's components to break down.