How to Find Baby Formula Right Now

Before you buy anything, check the first five or six ingredients listed on the back label — the ones that appear before the phrase “and less than 2 percent” in the ingredient list. It’s best to buy a new formula that matches the ingredients listed in your usual formula, Dr. Young said, to make for an easier transition for your baby. You should also pay attention to terms like “partially hydrolyzed” or “enzymatically hydrolyzed,” which refer to the size of the protein molecule in the formula. If you normally buy a formula that contains “partially hydrolyzed nonfat milk,” for instance, you’re best off buying a replacement formula that also contains partially hydrolyzed nonfat milk, Dr. Young explained.

If your baby is on a special formula because of prematurity or other health issues, double-check with your pediatrician before switching, Dr. Playforth suggested, just to be sure you’re making a safe choice.

Ideally, when you transition to a new formula, you want to do it gradually, Ms. Moore said, by mixing the old and new formulas separately before adding them to the same bottle. “For a couple of days, give three quarters of your normal formula with one quarter of the new formula. And then slowly increase the amount of the new formula and wean the amount of the old formula,” she said.

If you can’t transition gradually because you’ve run out of your usual formula, that’s OK — your baby will be fine, Ms. Moore said, although you might notice more gassiness or fussiness during the transition. That is expected, and normal, for the first two weeks after switching formulas, she added. If you do see worrying symptoms — such as blood in your baby’s stool, a rash or signs that your baby is having trouble breathing — they could be a sign of an allergy and you should stop feeding them the new formula and call your pediatrician immediately, Dr. Young said.

If you’re running low on formula, never dilute it. Continue to follow the preparation directions listed on the package. “Changing the ratio of formula to water can be extremely dangerous for infants and lead to water intoxication, electrolyte imbalances and seizures,” Dr. Playforth said.

Likewise, never make your own formula at home, as doing so can cause nutritional deficiencies and other health issues, Dr. Playforth added. A 2020 study analyzed 144 online baby formula recipes, finding that nearly half included ingredients that could cause food-borne illness.

Dr. Young does not recommend feeding babies under 1 formulas that are intended for toddlers, either, unless your pediatrician gives you permission. Even if the ingredients look similar, toddler formulas can contain amounts of certain ingredients, like vitamins, that are not safe for young babies. “If you have an infant, stick with an infant formula,” she said. Don’t feed your baby cow’s milk if they’re under 1 year old, either, she said, because the proteins can be difficult for infants to digest and may not provide essential nutrients.

The bottom line is that even if you can’t find your favorite baby formula, other options will work well. There are so many types of infant formulas on the market, Dr. Young said, that you’ll almost certainly be able to find one that nourishes your baby.

Melinda Wenner Moyer is a science journalist and the author of “How To Raise Kids Who Aren’t Assholes.”