Feeding Formula

Can You Mix or Switch Different Formulas? (Side Effects, Step By Step Guide)

Maybe you’re looking to switch formula brands to save some money given the expensive cost of baby formula?

Perhaps your baby is rejecting the taste of their formula and you cannot return any unopened bottles as you don’t have the receipt.

Or are you struggling to find your usual brand due to supply issues?

If you answered yes to any of these questions then there’s probably one burning question on your mind – is it ok to mix or switch different formulas?

In general, most products have the same basic ingredients, so it should be fine and safe to switch formula brands, as well as mix different brands of the same formula type together.

You should however familiarize yourself with the negative side effects your baby may face from a formula change, as well as the best way to transition from one brand to another.

So let’s take a look at mixing or switching formula brands in more detail.

Can You Mix Formulas Of The Same Brand?

While you might be understandably concerned about upsetting you baby’s stomach or causing avoidable fussiness, in general it’s absolutely fine to mix formulas of the same brand.

In fact, according to the AAP, for most babies it’s fine to switch between formula brands.

Formula must contain nutrients that help a baby grow and thrive, and FDA regulations state that there must be a minimum of 29 nutrients in baby formula (with 9 of those nutrients having a maximum allowable amount).

Given these strict guidelines, there are not as many differences between brands as you may think, so switching or mixing formulas is generally not an issue for most babies and toddlers.

Can You Mix Two Different Formulas Together?

A common question from many parents is whether it is ok to mix two different formulas together.

Fortunately the answer is yes, it’s generally fine to mix two different formulas together, provided you stick to the same type of formula and follow standard mixing, storage and preparation guidelines.

This is because most products contain very similar ingredients and use similar recipes, so in reality there is little difference between brands.

The exception is if your baby has been prescribed a certain type of formula from their pediatrician, in which case it’s best to check with them before making any changes.

photo of baby feeding

Is It OK To Switch Formula Within The Same Brand?

Yes, if you’re thinking about switching formula within the same brand then that’s generally fine.

It’s also considered fine to switch between powdered, concentrated liquid and ready to drink formula, provided your baby is able to drink all three (some premature babies are not able to drink powdered formula for the first few months).

Can You Mix Formula In The Same Bottle?

If you have different formulas you’re looking to use up, or want to give your baby two different formulas because they prefer the combined taste, then you’re probably wondering if it’s safe to mix formula in the same bottle.

Once again, the good news is that mixing formula in a bottle is fine, provided you follow all the usual instructions and measure the portion sizes correctly.

Can You Mix Two Different Similac Formulas?

Both Enfamil and Similac are popular and widely-available, so a frequent question from parents is whether it’s ok to mix two different products from these brands.

Provided you follow standard mixing instructions, there is no issue and it’s totally fine to mix two different Similac formulas.

Side Effects Of Switching Formula Brands?

Usually, if you’re making a switch from the same type of formula, your baby should not experience any major side effects.

However, some babies may be more sensitive than others when it comes to changes in their diet.

Some possible side effects from changing formula include:

  • Increased gassiness
  • Throwing up more often / excessive spit up
  • Changes in stools / poop consistency
  • Diarrhea (if excessive this may indicate your baby has an allergy to the new product)
  • Constipation
  • Increased fussiness – your baby may dislike the taste (or even refuses to drink) the new product

How To Switch Baby Formula (Step By Step Guide)

If possible, it’s generally better to change your baby’s formula gradually so you can keep track of any side effects including intolerances.

However, if you need to go cold turkey when making the switch (for example because you cannot find any supply of your normal formula), that should generally be fine and the side effects are usually negligible for most babies.

But if you still have some of your old product available, then you may want to follow this step by step guide on how to switch baby formula:

  1. Begin mixing 3 parts old formula with one part new.
  2. Once you’re satisfied your baby is happy with this mixture and there are no major side effects, you can move to a mixture of half and half.
  3. Assuming all is still okay, you can then move to 1/4 old and 3/4 new.
  4. After a few more days, if all is fine then move completely over to the new formula, so your baby’s bottle now consists 100% of the new product.

Many nutritionists  recommend making this change over a 1-2 week period if possible, to give your baby the best chance of liking the new formula and to avoid any potential stomach upsets.

See Also: Your Must Have Baby & Toddler Feeding Guide

Tori is mama to 3 year old Isabella and co-founder of Rockinbaby. She has a BSc in Psychology, is a certified yoga teacher and is a working mom. In her free time Tori loves cooking delicious foods and baked treats, entertaining and working out. Learn more about Tori here.

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