What happens if a baby drinks old formula?

What happens if a baby drinks old formula?

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In parenting, babies aren’t the only ones who evolve, you as the parents or caregivers evolve with them. You try processes and routines and pick the ones that work while changing the one that isn’t for you. You learn new things about the baby every day. The baby also learns new skills as he grows and you try to change your care to fit everything new about the baby.

As rewarding and beautiful as it all is, mistakes are also common with new parents and with parents who already have children. This happens because parenting can be overwhelming and exhausting and every baby is his own individual. One of those mistakes is feeding your baby old formula, which usually results in self-blame or blaming your partner. The most pertinent question moms ask at this stage is – what happens if a baby drinks old formula?

Therefore, in this article, we will discuss what happens if a baby drinks old formula, the effects of your baby drinking old formula, and what you can do about it.

How ‘old’ is old formula?

Studies by pediatricians have shown that the baby formula is considered old after two hours of its preparation. This is because of the formation of Cronobacter sakazakii, also known as Enterobacter Sakazakii. It is a naturally occurring germ that settles in dry food such as powdered milk, herbs, and your baby’s formula. It can cause illness in anybody but is dangerous in babies, especially premature babies and those with pre-existing medical conditions like immune system issues.

What happens if baby drinks old formula: Signs of an infection

Most moms will like to know what happens if a baby drinks spoiled formula milk? Below is some spoiled formula symptoms.


After your baby drinks old formula, the first thing you’ll notice is vomiting and some diarrhea. Vomiting is a process through which your baby’s system tries to get rid of the spoilt food. Some babies settle and recover after vomiting while others experience a fever which you need to see a doctor immediately.


If a baby drank spoiled formula, the body will want to detoxify itself through Diarrhea. The baby’s body passes the spoilt food differently than vomiting. Both these processes cause weakness and dehydration in your baby and may also affect how he feeds. You must note how frequently your baby vomits and give him some water to rehydrate, then see a doctor immediately.

Steps to take to prevent an infection

It is worth mentioning that although breastfeeding seems to cancel out much of the risk of bacterial infection, formula feeding works for many families. The key to keeping your child healthy and happy isn’t in suddenly switching from formula feeding to breastfeeding but in taking the right precautions regardless of what feeding method you are using. Precautions that may help include:

a.         Sanitize everything used in preparation and storage

There isn’t much you can do about the bacteria because it occurs naturally and settles on surfaces. However, maintaining good hygiene helps to prevent contamination of your baby’s food. Sanitize everything you used to prepare and store your baby’s meals. If you also pump breast milk, then sanitize all pump parts before and after use.

b.         Try using the liquid formula

Enterobacter Sakazakii seems to adhere to powdered products more than liquids. This means that using liquid formula reduces your baby’s risk of getting infected by the bacteria. However, the liquid formula must be kept according to the manufacturer’s instructions and should be tightly sealed.

c.         Don’t warm in the microwave

Warming the formula before feeding is unnecessary. However, if you intend to warm the milk formula or bottle, then the microwave is not your best bet. It doesn’t warm food evenly which leads to different patches of temperature variation throughout the meal which can favor bacterial growth.

d.         Take precautions during preparation and storage of formula

Ensure that the formula lid is tightly sealed in storage and cover the lead immediately after scooping what you need to prepare a meal. Ensure that the water you use in preparation is clean or has been boiled and cooled before use. Feed your baby within two hours of preparing the formula and throw away the leftover.

e.         Make sure your hands are clean!

Remember to wash your hands with soap and water immediately after using the toilet or changing your baby’s diapers. Wash your hands before preparing the formula or touching anything that will touch your baby’s mouth like the feeding bottles and pacifiers.

Some guidelines to help you to prevent your baby from drinking old formula.

a.         Always label your formula

To prevent your baby from drinking old formula, label your formula. Just like you would with expressed breast milk, write the date and time at which the formula was prepared. This allows your partner or caregiver to know which one to use first to prevent infections and wastage. This tagging system guides your caregivers to administer the older formula before the new ones.

b.         Throw away the old formula immediately  

There are guidelines regarding how long prepared and refrigerated formula can last. Some studies have shown that by maintaining the right temperature, the formula can remain viable for twenty-four hours. Therefore, a formula can go bad after an hour. However, discard the old formula as soon as possible. If you postpone throwing it away, the risk arises of someone feeding it to your baby unknowingly.

c.         Keep the formula away from contaminants

There is a need to devise a good strategy for formula milk storage. Any and everything that has the potential of making your baby fall sick if ingested should be kept far from the place you prepare the formula. An example of this is an old formula. The first few months are very critical to your baby, especially one with an existing condition, so be very careful with whatever touches your baby’s mouth.

d.         Be observant

It is possible for the milk to become infected even before it expires through contamination of the bottle or formula before preparation. As soon as your baby turns off or become less active accompanied by a fever or vomiting, see the doctor at once.

e.         Don’t play the blame game

It is very easy to dwell on how the baby falling sick was yours or your partner’s fault, but that solves nothing. Rather, identify what you both did wrong, seek counseling and direction from professionals, and work on doing better in the future.

FAQS About baby drinking old formula

What happens if you give a baby formula that is over an hour old?

The reason you cannot feed baby old formula is because of the bacteria in babies’ mouths. They get the bacteria from the nipples and they can transfer it to the formula. This can grow and then cause harm to the baby. However, some people go by the two hour rule. If your baby drinks formula that is an hour old, they may be fine. But you need to be careful.

What happens if the baby drinks a 2-hour old formula?

By the time the formula gets to the 2-hour mark, it is not safe for drinking. Giving baby formula after 2 hours can affect your baby’s health. This is because the bacteria in it would have grown and broken down the vitamins and nutrients in the formula. This means your baby would not be getting all the nutrients they need. If your baby drinks a 2-hour old formula, they may be sick.

What happens if you accidentally gave your baby old formula?

Whether it is by accident or not, it is still the same issue. Feeding your baby old formula can make them fall sick, especially if it is a formula that has been sitting out for over 2 hours.

Baby drank expired ready to feed formula

You’ve already fed the baby with the expired ready to feed formula, so there is nothing you can do about it. The baby might have an upset stomach. But don’t use the formula again, throw the rest of it out. If you bought the expired formula like that from the store, go back to the store and explain to them so you can get a refund. Always watch out for expired formulas. They smell worse and have different colors from the good formula.

Baby found an old bottle and drank it

In most cases, the baby may be alright. But otherwise, they will start showing spoiled formula symptoms by vomiting and having diarrhea. If they fell ill, you need to see your pediatrician immediately. But if they are not sick, there is nothing to worry about. The baby will just be fine.

Can you reheat formula?

Moms ask questions such as “can you reheat formula if a baby didn’t drink it? How many times can you reheat the formula? It depends on the scenario. One, if you make a bottle of formula and the baby did not drink out of it, you can reheat once. Second, if you prepare a bottle of formula for your baby and they didn’t finish drinking it, you should not reheat it or use it again. It should be thrown away.

Can you mix formula with breast milk?

Yes, you can mix formula with breast milk for your baby. You can even do it inside the same bottle.

Can I put a leftover formula in the fridge?

No. You cannot use leftover formula, so don’t bother putting it in the fridge. It is susceptible to bacteria.

How long can Similac stay out?

According to Similac, Formula made from Similac powder should be used within 24 hours. Similac ready-to-feed formulas must be used within 48 to 72 hours after opening. Both the powder and ready to feed formula after being mixed or opened must be stored in the refrigerator until you are ready to feed the baby.

How long does Enfamil ready to use formula last?

Enfamil Ready to use formula can last up to 48 hours if kept covered or sealed in the refrigerator.

Baby didn’t finish bottle of formula can I reuse?

You cannot reuse an unfinished bottle of formula because bacteria grow faster in it. However, you stop wasting the formula by using a formula pitcher, such as Dr. Brown’s formula pitcher. You can mix all the formula the baby will drink through the day in it and put it in the fridge, then pour what you need into bottles throughout the day and warm.

Can you reheat formula if baby didn’t drink it?

There are times you prepare formula for your baby and the baby ends up not drinking it. At such time, can you reheat the formula if the baby didn’t drink it. Especially if the formula is cold. You can only reheat the formula if the baby has not had the nipple in their mouth. You can keep the bottle of formula in the fridge for about 24 hrs and then you can reheat it in water or a bottle warmer.

How long can I keep formula milk in the fridge?

You can keep formula milk in the fridge for 24hrs.

How long does formula last?

Prepared infant formula can only last for 2 hours. It can last for up to 24 hrs.


Now you know what happens if a baby drinks old formula and what to do about it. It is very important to take the right precautions when preparing your baby’s formula, especially if he has a weak immune system. Some infections can lead to death. Remember that a formula can only last for 24 hours after mixing under the right temperature and storage. However, it can also go bad after an hour without proper storage.

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