How should I prepare and store infant formula?

Prepare powdered formula safely

Wash your hands, clean and sanitize the preparation area, and use clean feeding equipment. Follow the formula container for the amount of water and powder. CDC guidance says to measure the water first, then add the powder. Changing the proportions can make formula unsafe or nutritionally unsuitable.

This article focuses on powdered formula. For ready to feed or liquid concentrate products, follow the container instructions and local health advice instead of applying powdered formula steps. The CDC says most babies can have powdered formula mixed with water that is safe to drink by following the container instructions. Powdered formula isn’t sterile. For babies younger than two months, born prematurely or with a weakened immune system, current U.S. CDC guidance calls for extra steps: boil the water, wait about five minutes before mixing, then cool the formula before feeding. Ask your baby's doctor or local public health service which instructions apply.

How long can prepared formula sit out?

Current U.S. CDC guidance says to use prepared formula within two hours of preparation and within one hour from when a feed begins. If you won’t start using it within two hours, put it in the refrigerator right away and use it within 24 hours. Throw away formula left in a bottle after a feed because saliva can allow bacteria to grow.

Formula doesn’t need to be warmed. Never microwave a bottle because uneven heating can create hot spots. If you choose to warm it, the CDC describes placing the bottle under running warm water and checking a few drops on your wrist before feeding.

Keep an opened container of powdered formula in a cool, dry place with its lid closed, not in the refrigerator. Most formulas should be used within one month of opening, but check the container label. Never use formula after its use by date.

Keep a feed record separate from formula safety

A feed log can note when a bottle was offered and how much your baby drank. It can’t tell you how much formula to prepare, confirm that formula was stored safely or decide whether an amount is right for your baby. Follow any plan from your midwife or doctor.

If you’re recording nursing and bottles, see how to keep mixed feeding records clear. The preparation steps here summarize U.S. CDC guidance. Instructions can differ by country, water safety and a baby's health.