How Long Is Formula Good For? Can You Mix Formula & Breast Milk?

How Long Is Formula Good For

A common question parents ask is, ‘How long is formula good for?

Baby formula is a great alternative when feeding your baby, if you don’t want or can’t breastfeed for whatever reason.

Infant formula has been designed to replicate breast milk and provide your little one with all the nutrients, proteins, carbohydrates, fats, and vitamins they need to grow and develop properly in every stage of their lives.

You can find it in many forms, such as powdered formula, ready-to-feed formula, and concentrate. Choosing which one to use will depend on the availability and what better fits your lifestyle because they all offer the same benefits to your baby.

The most commonly used, especially on older babies, is powdered formula because it’s very convenient and can be prepared on the go. However, when you’re tired and dealing with a small baby, it’s natural to be tempted to plan ahead and want to pre-mix your formula for later.

This can be tricky if it’s not done correctly, and to avoid food poisoning or bacterial infections in your baby, you need to follow specific guidelines.

Here’s what we’ve learned about how long formula is good for and some formula-feeding FAQS.

How long can formula sit out, and how long is formula good for?

The general rule is that formula can sit out 1hr to 48hrs, depending on a variety of factors.

  • Ready-to-feed formula comes in different sizes, and some brands are designed to be used to feed your baby directly from the container if you attach a special nipple to it. This formula is usually used with newborn babies and comes in 2oz bottles. There are also larger bottles that you can divide and use as needed. According to manufacturing instructions, this formula can be used within 48 hours if kept refrigerated and as long as your baby hasn’t fed directly from the container. If the bottles haven’t been opened, you can store them in your pantry for the time shown on the label (expiration date), but it needs to be consumed or refrigerated as soon as you open them.
  • Concentrated formula requires you to add water to it before consuming it. The prepared formula can be kept in the refrigerator for up to 24 hours if your baby hasn’t directly fed from it. And the same principle applies to powdered infant formula; it needs to be consumed within 24 hours of being prepared and refrigerated.

What happens if you feed your baby formula and there are leftovers? Unfortunately, this leftover formula needs to be consumed within 1 hour. Otherwise, you’ll need to throw it away because the bacteria in your baby’s saliva will transfer to the milk and contaminate it, leading to bacterial growth that can make your baby sick.

Also, if you warm formula and there’s some leftover, you’ll need to either feed it to your baby in the next 60 minutes or throw it out because the temperature will enable bacterial growth, and it’s a risk you won’t want to take.

So warmed formula or leftover formula from a previous feeding that has been in contact with your baby’s mouth needs to be used in the next hour starting from the time feeding begins or discarded. If you want to save time preparing bottles of formula safely, store them in the refrigerator, with the lid tightly closed, and only pour into the bottle the exact amount your baby drinks in one sitting.

How Long Is Formula Good For

Also, trust in your instinct and common sense. If you notice that the prepared formula looks curdled and clumpy, smells foul, and tastes sour, it’s safe to say it’s not safe for consumption because it has spoilt and needs to be discarded.

An important thing to note is that you should not freeze prepared infant formula like breast milk. This is because this separates it and may brake the nutrients. Powdered formula should be stored in a cool and dry place. Still, it should not be frozen or kept in the refrigerator because moisture will clump it and make preparing the formula difficult because it will not mix easily with the water. You need it to have zero clumps or solids before feeding it to your baby.

For that reason, manufacturers recommend using powdered formula within a month after opening the container, regardless of the expiration date on the label or bottom of most cans.

In the case of babies that have been born prematurely, have a weakened immune system, or are very young (from newborn up until the 3rd month), you must follow the preparation and storage guidelines because mishandling infant formula may lead to serious health issues.

How should I prepare formula?

One of the benefits of the ready-to-feed formula is that you can simply put in your baby’s bottle and give it to them without much fuss, and it lasts more time in the refrigerator than powdered or concentrated formulas. This is because it’s made with high controls and sterilized components to prevent any possibility of contamination.

But if you’re using concentrated or powdered formula, you’ll need to add tap water to make it consumable. To safely prepare formula and avoid harmful bacteria, there are some guidelines you’ll need to follow.

You’ll need boiled water, preferably bottled water, that you’ve let cool down for around 30 minutes or at room temperature. It’s important to read the package directions closely to add the exact amount of water to the exact amount of infant formula you want to prepare because wrong measurements can either dilute the nutrients or cause harm to the baby if not prepared properly.

You should first add the water to the bottle and then add formula powder scoops with powdered formula. This is because if you first add the formula to the bottle and then want to measure the water with the same bottle, it won’t be reliable. After adding the formula, you’ll need to swirl or shake the bottle until it’s completely dissolved and mixed.

Keep in mind that when bottle feeding your baby, you’ll need to keep a close eye on the sanitation and cleanliness of the process. Before preparing the formula, wash your hands and always use clean bottles.

Every bottle needs to be sterilized before using it the first time; you can do this with a sterilizer, microwaveable steam bags, or by placing the bottle and all its components in a pot with water that you’ll bring up to a rolling boil. Leave the bottles in the boiling water for around 5 minutes before retrieving them.

After the first sterilization, wash bottles with soapy water and rinse with hot water to maintain cleanliness.

Warming formula milk

The decision to feed warm formula to your baby is a matter of preference because, just as with breast milk, liquid formula can be given to your baby warm, cool, or at room temperature.

If you decide you want to warm the baby formula, you can use a bottle warmer or place the bottle with formula in a bowl of warm water to slowly achieve the desired temperature safely. Another way to do this is by placing the bottle under running hot water.

What should not be done is microwave formula because this raises the temperature unevenly and may affect the nutrients in the milk, and create hot spots that may burn your baby’s mouth.

Before giving your baby any warmed milk, you should drop a little of the milk into your forearm or wrist to test the temperature.

Formula that’s been warmed should be used within two hours tops. You shouldn’t save leftover formula from this feeding for more than one hour, neither at room temperature nor in the refrigerator, because it’s been contaminated and combined with the raised temperature, it may harbor harmful bacteria.

Formula feeding guidelines

Can you mix formula and breastmilk?

The short answer is yes; you can mix formula and breastmilk.

Whether you have a mixed feeding approach, where you breastfeed for some sessions and formula feed for others, there’s no evidence that it can harm your baby. In fact, studies have shown that this offers many benefits because it may fortify your baby’s nutrition and allow a little bit of independence for the mother.

There are times when exclusively breastfeeding can become too much for a person because it requires a lot of time, perseverance, and emotional dedication. It’s not uncommon to find burned-out mothers because they’ve put too much pressure on themselves to breastfeed exclusively.

Baby formula is an excellent alternative to help you in those cases. And it’s also been proven that mixing formula and breastmilk in the same bottle is safe for your baby.

To do this, you’ll need to follow your infant formula preparation guidelines as we’ve explained above or as shown in the instructions label, and once it’s ready, you can mix it with breast milk to give to your baby.

Keep in mind that guidelines for storing breast milk and for storing formula safely may vary, but since formula has shorter storage times and needs to be consumed sooner than breastmilk when combining them in the same bottle, you’ll need to adhere to the safety precautions of formula.

This means that it’s recommended that you only mix the exact amount you will feed your baby at one sitting and that once the baby drinks from that bottle, the leftover should be consumed within one hour or thrown out.

Formula mixed with breastmilk should not be frozen either, not even ready to feed formula.

Some of the benefits of mixing formula and breastmilk, whether in a combined approach or in the same bottle, include that it allows the baby to adjust to the formula’s taste easier, especially in cases where you need to use hypoallergenic or specialized formulas that have a very strong taste and smell and that your baby may initially reject.

Also, formula satisfies babies for longer periods because their bodies take more time processing it than breastmilk. This means that they will sleep longer between feeds, so if you want to rest more, this can be the answer to your prayers.

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