Choosing and preparing formula

Choosing a formula

For most babies, a standard cow’s milk-based infant formula is the right choice. The NHS calls it first infant formula: it’s suitable from birth, and it’s the only formula most babies need for the whole first year, including after solids start.

You don’t need the most expensive brand:

• US: every infant formula sold in the US, store brands included, must meet FDA minimum nutrition and safety requirements (AAP). The AAP recommends iron-fortified formula for all babies who aren’t breastfed, or are only partly breastfed, until age 1. Low-iron formulas shouldn’t be used, and the AAP says the iron in formula doesn’t cause constipation.
• UK: all infant formula has to meet the same standards, so a cheaper brand is just as good (NHS).

Formula comes as powder, concentrated liquid and ready-to-feed liquid (AAP). Ready-to-feed is convenient and doesn’t need water, but it costs more and has to be used sooner once opened (NHS).

Other types of formula

Ask your pediatrician, GP or health visitor before using any of these:

• Goat’s milk formula: made to the same standards as cow’s milk formula. It’s not suitable for babies with a cow’s milk allergy, because the proteins are very similar (NHS, AAP).
• Extensively hydrolyzed formula: for babies with a diagnosed cow’s milk allergy, recommended or prescribed by a doctor (AAP, NHS). In the UK, some formulas in shops are labeled “hypoallergenic”, but the NHS says these aren’t suitable for a diagnosed cow’s milk allergy: use the fully hydrolyzed formula your GP prescribes.
• “Comfort” or partially hydrolyzed formula: the NHS says there’s no evidence it helps colic or constipation, and it’s not suitable for a cow’s milk allergy.
• Lactose-free formula: lactose intolerance is rare in babies, so check with your doctor first (AAP, NHS).
• Soy formula: the NHS says only from 6 months and only under medical advice. The AAP says it’s rarely the right choice and isn’t recommended for a cow’s milk allergy, because up to half of babies with milk allergy also react to soy.
• Anti-reflux formula: only on medical advice (NHS).
• Follow-on formula: never under 6 months, and no benefit after (NHS). Toddler milks: not under 12 months (AAP).

If you think your baby is reacting to their formula, talk to your doctor before switching. See cow’s milk allergy.

Never homemade, never watered down

Never make homemade formula. The AAP says homemade formula may not be safe or give your baby the right balance of nutrients, and some babies fed it have been hospitalized with low calcium and rickets.

Also never give a baby under 1:

• cow’s milk, goat’s milk or plant drinks (soy, oat, almond, rice) as their milk feed
• condensed, evaporated or dried milk (NHS)
• formulas imported without FDA registration, from unreliable online sellers (AAP)

Never add extra water. The AAP explains that diluted formula gives your baby fewer nutrients, which can slow growth, and too much water can upset the balance of salts like sodium in the body, leading to seizures.

Never add extra powder either. Too little water makes your baby’s kidneys and digestive system work too hard and can cause dehydration (CDC) or constipation (NHS).

Don’t add sugar, cereal or anything else to a bottle (NHS).

If you’re struggling to afford formula, don’t stretch it. Ask your pediatrician, WIC, your local health department or a food pantry for help. You can also dial 2-1-1 (AAP).Talk to your health visitor or GP about help that’s available.Ask your doctor or local health service about help that’s available.

Making up a bottle: the shared steps

Both US and UK advice agree on these:

1. Wash your hands and clean the surface you’ll use.
2. Use clean bottles. The CDC says bottles need to be clean and sanitized. The NHS says to sterilize bottles and teats until your baby is at least 12 months old.
3. Read the label. Brands differ in how much water and powder to use.
4. Water first, then powder. Measure the water into the bottle, then add the powder (CDC, AAP, NHS).
5. Use only the scoop that came with that formula, loosely filled and leveled off with a clean knife or the leveler (NHS).
6. Cap and shake until the powder dissolves.
7. Check the temperature. Shake a few drops on the inside of your wrist: it should feel warm, not hot.

The water: where advice differs most

Powdered formula isn’t sterile. It can occasionally contain bacteria such as Cronobacter, which are rare but can make young babies very ill (CDC, NHS). The US and UK handle this risk differently.

US (CDC, AAP)

• Most babies, most of the time: use water from a safe source and follow the label. Tap water can be filtered or unfiltered, and room-temperature water is fine. If you’re not sure your tap water is safe, ask your local health department.
• Babies under 2 months, born before 37 weeks, or with a weakened immune system: boil the water, then wait about 5 minutes before mixing. Water around 158°F (70°C) kills Cronobacter. Cool the bottle before feeding.
• Emergencies (flood, water main break): use bottled water. If tap water is your only option, boil or disinfect it. For most babies, let boiled water cool to room temperature before mixing. If your baby is under 2 months, was born before 37 weeks or has a weakened immune system, follow the very hot water steps above instead. Boiling doesn’t remove chemicals: if the water may be chemically contaminated, use bottled water or ready-to-feed formula and follow local public health advice (CDC).
• Some formula labels give their own water instructions. Follow them.

UK (NHS)

• Every baby, every feed: fill the kettle with at least 1 liter of fresh tap water (not water that’s been boiled before), boil it, and let it cool for no more than 30 minutes, so it’s still at least 70°C.
• Pour the hot water into the bottle, add the powder, then cool the capped bottle under cold running water.
• Make up feeds one at a time, as your baby needs them.
• Don’t use artificially softened water. Bottled water isn’t usually recommended because it isn’t sterile and may contain too much sodium or sulphate.
• Formula machines: check the water comes out at 70°C or hotter, using a food thermometer.
• Some anti-reflux formulas say to use cooler water. Follow the pack, and take extra care with hygiene and storage.

Can I use distilled or bottled water?

US (CDC, AAP): yes, some of the time. Safe tap water is fine for most babies, and the AAP says it’s best to use it most of the time. The CDC says to use bottled water if your tap water isn’t safe. Two things to know:

• Fluoride. Water labeled distilled, purified, deionized or demineralized has no fluoride or only trace amounts, unless fluoride is listed as added (CDC). If your baby has only formula made with fluoridated tap water, there may be a higher chance of mild dental fluorosis, which only develops while teeth are forming under the gums (CDC). The CDC says using low-fluoride bottled water some of the time lowers this chance, and the AAP suggests mainly using safe fluoridated tap water with occasional non-fluoridated bottled water. Ready-to-feed formula contains little fluoride (CDC).
• The very hot water step still applies. For babies under 2 months, born before 37 weeks or with a weakened immune system, mix the powder with water that was boiled and left for about 5 minutes, whatever water you use (CDC). The germs it targets, such as Cronobacter, can be in the powder itself.

UK (NHS): use fresh tap water, boiled and still at least 70°C. The NHS says bottled water isn’t usually recommended, because it isn’t sterile and may contain too much sodium or sulphate. Use it only if tap water is unavailable or contaminated, and still boil it and follow the same steps. This advice covers all bottled water; the NHS doesn’t mention distilled water separately.

Storing and warming

• Feed soon. The CDC says use prepared formula within 2 hours of making it, and within 1 hour of the start of a feed.
• Fridge: if you won’t use it within 2 hours, refrigerate it straight away and use it within 24 hours (CDC, AAP).
• Leftovers: throw away any formula left in the bottle after a feed (CDC, NHS). Saliva in the milk lets bacteria grow.
• Opened ready-to-feed or concentrated liquid: cover, refrigerate and use within 48 hours (AAP).
• Opened powder: keep it in a cool, dry place with the lid closed, not in the fridge. Most need to be used within 1 month of opening, so check the label (CDC).
• Use-by date: never use formula after it (CDC).
• Warming isn’t needed (CDC). If you do warm a bottle, stand it in or hold it under warm water, keeping the water out of the bottle and off the nipple (CDC). Never use a microwave: it heats unevenly and can burn your baby’s mouth (CDC, NHS).

Out and about (NHS): carry measured powder, an empty sterilized bottle and a vacuum flask of just-boiled water, and make up the feed when needed, or use ready-to-feed cartons. Only if you have no other option, as a one-off and not regularly: make the feed at home, cool it and chill it in the fridge until cold, then carry it in a cool bag with an ice pack and use it within 4 hours (2 hours without an ice pack).

Where US and UK advice differs

• Water temperature. CDC and AAP: safe tap water, following the label, for most babies (the AAP describes using room-temperature tap water); boiled water cooled for about 5 minutes for babies under 2 months, born early, or with a weakened immune system. NHS: boiled water still at least 70°C for every feed, for every baby.
• Making bottles ahead. CDC and AAP: a prepared bottle can be kept in the fridge for up to 24 hours. NHS: make each feed fresh when it’s needed, and only transport a made-up feed when there’s no other option.
• Bottled water. CDC: fine when tap water isn’t safe. NHS: not usually recommended, except when tap water is unavailable or contaminated.
• Distilled water and fluoride. CDC: low-fluoride bottled water, such as distilled, can be used some of the time to lower the chance of mild fluorosis. AAP: mainly use safe fluoridated tap water, with occasional non-fluoridated bottled water. NHS: boiled tap water; its formula pages don’t discuss fluoride.
• Sterilizing. NHS: sterilize bottles and teats until 12 months. CDC: clean and sanitize bottles.
• Soy formula. NHS: from 6 months, only with medical advice. AAP: rarely needed, and not for cow’s milk allergy.

For how much to offer, see how much breast milk or formula.