Should You Mix or Switch Between Baby Formula Brands?

Mother feeding newborn a bottle

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In general, different brands of the same type of formula have the same basic ingredients. Switching between formula brands is not a problem, even though many parents wonder if doing so may cause fussiness or stool changes in their baby.

In fact, you can even mix different brands of the same type of formula together if you feel that your baby responds better to a mixture of one brand with another.

Which brands you choose to mix together depends on personal preference. You just need to be aware of the basic ingredients found in the same type of formula. As long as you are following standard mixing instructions, it is safe to mix formula brands.

Why Switch Formulas

You may be considering changing your baby's formula for a variety of reasons. If your baby is gassy, not sleeping well, or fussy, you might wonder if the formula is to blame. Price, availability, and ease of preparation may also prompt you to try something new.

Whatever the reason, there are a few formula basics to keep in mind before making the switch.

All milk-based, iron-fortified formulas (the type recommended for most infants) contain cow's milk as the protein source and lactose as the carbohydrate. Small variations, including different combinations of whey and casein proteins, do exist among milk-based formulas. The fat sources in these formulas are provided by different types of oils.

Types of Protein in Formula

There are three main types of protein found in baby formulas.

  • Cow's milk protein is the most common.
  • Soy protein is sometimes an option for infants with certain health conditions or an allergy to casein or whey, the two proteins found in cow's milk.
  • Hypoallergenic (also known as elemental) formulas contain protein that has been broken down into smaller parts. These formulas are expensive, most of them don't taste very good, and they are typically used for babies who cannot digest intact protein.

When switching to a new brand of formula, be sure to stick with the same type of protein. If you want to switch to a formula with a different protein source, check with your doctor first.

Contrary to popular belief, spitting up or excess gas in your baby is usually not due to the type of protein in the formula. Still, switching between brands can help parents see if their baby has any reaction to a particular brand.

The biggest difference between formulas is usually taste. Some children are quite picky about what they eat and may prefer one formula over another.

However, considering that the taste of breast milk changes depending on what a breastfeeding mother eats, flavor is not usually a huge factor for most formula-fed babies.

Below are some indications that your baby may have a true formula allergy:

  • Diarrhea
  • Abdominal cramping
  • Blood in a baby's stool or vomit
  • Hives or other skin rashes

If you notice any of these signs, call your pediatrician right away.

Experimenting with formulas for your baby can help ease worries about food intolerances, burping, constipation, excess gas or spit up, but in most cases it’s not necessary. As long as your baby is healthy and not showing signs of true formula intolerance or allergy, the formula you use really depends on personal preference.

Formula Safety

All brands of baby formula on the market are safe to use and must meet nutrient requirements set forth by the U.S. Food and Drug Administration (FDA). While brand-name and generic formulas may have slightly different ingredients, they must both adhere to the same federal requirements for nutrition and safety.

At the store, be sure to check the expiration date before buying any new container of formula. If you order online, check the date before opening it so that you can return anything that is expired. Also pay attention to any off-odors, colors, or flavors when opening and mixing the formula.

Only buy your formula from reputable retailers, as expired formulas are sometimes repackaged and sold with altered nutrition information. Feeding your infant a formula that is out-of-date or one that contains different ingredients could have serious consequences, especially if your baby already has health concerns.

The FDA recommends calling the formula manufacturer's toll-free number (listed on the container) if you notice anything wrong with your baby's formula.

It's important to follow the mixing instructions that are printed on each container of formula. Don't assume that because your standard formula says to use a certain ratio of water to powder, the new formula will be the same.

Although it may be tempting to save money or change the taste of your baby's formula by watering it down, this is never a good idea. Formula (especially ready-to-feed) is expensive, but it is the only source of nutrition for most infants (depending on their age.)

Adding too much water will lower the amount of calories and nutrients your baby consumes and can affect their growth and overall health.

If you are mixing two brands of formula, prepare each brand separately using the instructions for each one. This way you can be sure the concentrations of each are correct. Then combine the two prepared formulas in your baby's bottle.

How to Make a Switch

If you are switching formulas on your pediatrician's recommendation (to a hypoallergenic formula due to an allergy, for instance) you will probably be advised to discontinue the old formula and switch to the new one all at once.

If, however, you are switching for other reasons such as price or convenience, you can give the new formula a try and see how your baby likes it.

Keep in mind that it may take a few feedings before your baby gets used to the taste of a new formula.

Try making a gradual change if your baby does not seem to like the new choice of formula. You can start with a combination of three parts old to one part new, and when your baby accepts that, move to half-and-half.

Keep gradually changing the ratio until you are feeding only the new formula. You may want to buy a small container of the new formula until you know for sure you want to stick with it.

If you are concerned about gassiness, stick to one brand for at least a week or two to see if there are any changes in gas, stool, spit-up or burping. Your baby's digestive system needs this long to adjust to the new diet.

With a little planning, even if cost and convenience are how you are choosing a formula, you should be able to stick with one brand in the long run.

9 Sources
Verywell Family uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
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By Vincent Iannelli, MD
Vincent Iannelli, MD, is a board-certified pediatrician and fellow of the American Academy of Pediatrics. Dr. Iannelli has cared for children for more than 20 years.