Which Baby Formula Is Best? Choosing and Switching Formulas

The short version

For most healthy, full-term babies, a standard iron-fortified, cow's-milk-based formula is the right choice. Every infant formula sold in the US must meet the same FDA nutrient and safety requirements, so store brands are as nutritious as name brands, often for much less.

Formula types and what the evidence says

• Standard cow's milk-based: fits most babies. Added DHA, prebiotics or human-milk oligosaccharides are common now; possible benefits are modest.
• Partially hydrolyzed ("gentle" or "comfort"): proteins broken into smaller pieces. Some parents notice less fussiness, but evidence is weak, and the AAP says it doesn't prevent allergies. Not for a baby with milk allergy.
• Extensively hydrolyzed: proteins broken down much further. The usual first choice for cow's milk protein allergy, ideally with the pediatrician's guidance.
• Amino acid-based: for babies whose allergy doesn't settle on extensively hydrolyzed formula or who have severe allergy. Usually prescribed.
• Soy: for galactosemia or families avoiding animal products. Not a cure for colic or fussiness, not recommended for preterm babies, and some babies with milk allergy react to soy too.
• Lactose-reduced or lactose-free: true lactose intolerance is rare in babies. Little evidence it helps fussiness, but it's safe.
• Added rice or thickened ("AR", anti-reflux): may reduce how much milk comes back up, but doesn't treat reflux disease. Never thicken bottles yourself with cereal unless prescribed.
• Organic: meets the same standards; the choice is about preference and cost.
• Avoid low-iron formula, homemade formula, unregulated imports and toddler formula for babies under 12 months.

Switching formulas

• Moving between standard formulas, including brand to store brand, is usually fine straight away. If you like, mix old and new over a few days.
• Expect some change in stool color, smell or texture.
• Frequent switching rarely fixes fussiness, gas or spit-up, which are common and usually improve with time. Give a new formula about 1-2 weeks, and check basics first: paced feeding, nipple flow, burping and amounts (see the paced bottle feeding and nipple flow guides).
• Talk to the pediatrician before changing to a specialty formula. A real allergy needs a plan, and some specialty formulas cost far more.

Possible cow's milk protein allergy

• Signs: streaks of blood or mucus in the stool, frequent vomiting, hives or a rash after feeds, eczema that flares, ongoing diarrhea, poor weight gain, or extreme fussiness with feeds.
• It affects roughly 2-3 in 100 babies and usually shows up in the first months. Most outgrow it, many by their first birthday and most by school age.
• Breastfed babies can react to dairy in the parent's diet. Don't cut foods without guidance.

Vitamin D and iron

• Babies drinking about 32 oz (about 1 liter) of formula a day get enough vitamin D. Babies drinking less, or getting any breast milk, usually need a vitamin D supplement; ask the pediatrician.
• Choose iron-fortified formula. The iron does not cause constipation.

When to check in

Mention it at the next visit if: - Fussiness, gas or spit-up worries you, or you're considering a specialty formula. - You need help affording formula (WIC can help).

Call the pediatrician the same day for blood in the stool, repeated or forceful vomiting, few wet diapers, hives or a rash after a feed, or a temperature of 100.4°F (38°C) or higher in a baby under 3 months; call 911 for swelling of the lips or face, trouble breathing, or repeated vomiting with paleness or floppiness.