Most healthy, full-term babies do well on a standard cow’s milk-based formula, which accounts for the majority of formula sold. The real decision comes down to your baby’s tolerance, any allergies or digestive issues, and a few ingredient details worth checking on the label. Here’s how to narrow it down.
Start With the Four Main Types
Infant formulas fall into four broad categories, and the right one depends almost entirely on how your baby digests protein.
- Cow’s milk-based: The default for most infants. The protein is modified to be more digestible than actual cow’s milk, and it provides complete nutrition. Unless your baby shows signs of intolerance, this is where to start.
- Soy-based: Built on soy protein instead of dairy. The American Academy of Pediatrics notes that the medical reasons to choose soy are narrow: galactosemia (a rare disorder where a baby can’t process one of the sugars in lactose), hereditary lactase deficiency (extremely rare), or a family preference for a vegetarian diet. Soy is not a reliable alternative for babies with cow’s milk allergy, because up to half of those babies also react to soy protein.
- Extensively hydrolyzed: Sometimes called “predigested” formula. The milk protein is broken into much smaller pieces so the immune system is less likely to react. This is the first step for babies diagnosed with cow’s milk protein allergy (CMPA) and resolves symptoms in roughly 90% of cases.
- Amino acid-based (elemental): The protein is broken down to its most basic building blocks. About 10% of babies with CMPA still react to hydrolyzed formula and need this version. It’s also recommended as a first-line option for babies with eosinophilic esophagitis or a history of anaphylaxis to milk protein.
If your baby is spitting up, gassy, or fussy on a standard formula, that doesn’t automatically mean an allergy. Many babies are simply adjusting. Persistent symptoms like blood in the stool, severe eczema, vomiting after most feedings, or poor weight gain are the signals that point toward a true protein allergy and a need to move up the ladder to hydrolyzed or amino acid-based options.
What to Look for on the Label
Once you’ve settled on a formula type, the ingredient list can still vary from brand to brand. A few things are worth checking.
DHA and ARA
These are long-chain fatty acids that play a direct role in brain, retina, and immune system development. They occur naturally in breast milk, and research has found a strong positive correlation between breast milk DHA levels and children’s IQ scores. Deficiency in either fatty acid can impair visual and cognitive development. The European Union requires a minimum of 20 mg of DHA per 100 kilocalories in infant formula. Not all formulas list these amounts prominently, but most major brands now include both. If you’re comparing products, check that DHA is present and that ARA is included at a level at least equal to the DHA.
Prebiotics
Many formulas now add prebiotics, typically a mix of galacto-oligosaccharides (GOS) and fructo-oligosaccharides (FOS), to mimic the fermentable sugars found naturally in breast milk. These feed beneficial gut bacteria. A meta-analysis of seven studies found that babies fed prebiotic-supplemented formula had significantly higher levels of Bifidobacterium (a key beneficial microbe) compared to babies on standard formula. Prebiotic formulas also produced lower fecal pH, which is a marker of a healthier gut environment similar to that of breastfed infants. All European formulas include prebiotics or probiotics. In the U.S., many but not all brands do, so it’s worth a glance at the label.
Fat Sources
Some formulas use palm oil or palm olein as a fat source because its fatty acid profile resembles that of breast milk fat. However, research has found that formulas containing palm oil may reduce calcium and total fat absorption compared to formulas using other vegetable oil blends. The studies are mixed and hard to compare directly, but if you’re choosing between two otherwise similar products, a formula without palm oil as the primary fat is a reasonable preference.
Carbohydrate Source
Most standard formulas in both Europe and the U.S. use 100% lactose as the primary carbohydrate, which is the same sugar found in breast milk. Some “sensitive” or “gentle” formulas partially replace lactose with maltodextrin or starch to ease digestion for gassy babies. Lactose is the better default unless your baby has a specific reason to avoid it.
Powder, Concentrate, or Ready-to-Feed
Formula comes in three formats, and the tradeoffs are straightforward.
Powdered formula is the most economical option, running roughly $0.30 to $0.32 per ounce once mixed. You control exactly how much you prepare, so there’s less waste. The downside is that powdered formula is not sterile. It can harbor bacteria like Cronobacter, which is rare but dangerous for newborns. The CDC recommends boiling water and letting it cool for about five minutes (to around 158°F) before mixing with powder. This temperature is hot enough to kill Cronobacter while still being safe to work with.
Liquid concentrate splits the difference. You dilute it with water, so it’s slightly more convenient than powder but still requires careful measurement and clean water.
Ready-to-feed is sterile, requires no mixing, and is the safest option for premature or immunocompromised newborns. The per-ounce cost can be comparable to powder when bought in bulk (around $0.30 per ounce for large bottles), but in practice it’s more expensive because any formula left in an opened container must be used or discarded within a set window. You can’t make a precise two-ounce bottle the way you can with powder, so waste adds up.
Many parents use ready-to-feed for the first few weeks when a newborn’s immune system is most vulnerable, then switch to powder as the baby grows. That’s a practical compromise.
How to Store Prepared Formula Safely
Once you mix or open formula, bacteria can grow quickly. Use prepared formula within two hours of mixing. Once a feeding starts, finish the bottle within one hour, because bacteria from a baby’s mouth enter the formula through the nipple. If you prepare bottles in advance, refrigerate them immediately and use within 24 hours. Discard anything that sits out longer than these windows, even if it looks and smells fine.
U.S. vs. European Formulas
European brands like HiPP and Holle have gained a following among American parents who see them as higher quality. There are real differences in standards. European formulas typically contain less iron than U.S. formulas, which are formulated to meet higher AAP recommendations. European formulas universally include prebiotics and probiotics, while that’s optional in the U.S. European “sensitive” lines more commonly use maltodextrin or starch instead of corn syrup solids as an alternative carbohydrate.
The practical concern with buying European formula is that products not sold through official U.S. channels haven’t gone through FDA review. They may also have been shipped or stored under conditions that aren’t monitored, and the labels won’t include English-language preparation instructions that match U.S. measuring standards. Children’s Hospital Colorado notes that this lack of regulatory oversight is the main risk, not the formula itself. If you choose a European brand, buy from a reputable retailer and follow the preparation instructions precisely.
Switching Formulas
Trying a new formula doesn’t require a gradual transition. You can switch from one feeding to the next. Give any new formula at least a full week before deciding it isn’t working, because many babies need a few days to adjust. Minor changes in stool color, frequency, or gas are normal during a switch and don’t mean the formula is wrong. Persistent crying, vomiting, diarrhea, rash, or refusal to eat after a week are signs the formula isn’t a good fit.
Store brands and generics sold in the U.S. are required to meet the same FDA nutritional standards as name brands. The protein source, vitamin levels, and calorie density are functionally identical. Switching to a store brand to save money is a reasonable choice that doesn’t compromise nutrition.