What Happens If Baby Drinks Old Formula – Sometimes, when you make formula for your baby, you forget how long it has been out. Formula that is out for a certain amount of time can go spoiled and make your baby sick. When parents see their child drinking formula and they think the formula is a little old, they are worried that their child can be sick while they get rid of the formula. What happens if baby drinks old formula?

How Long Is Formula Good Until It Spoils

When you make your baby formula and realize that they are not hungry at the moment or they just ate, you may find yourself making one too many bottles. How long is formula good until it spoils? Once formula is made, the CDC states that it can be consumed up to two hours in regular indoor temperatures before it goes bad. If your baby has started to drink the formula and stopped, the formula is good for an hour. If it is refrigerated, it can last up to two days. Your refrigerator should always be at 4.4 C /39 F or lower for storing your babies formula.

Remember to read the box of formula when you purchase it to ensure the rules and regulations of storing formula and how long it is suitable for babies drinking. It is possible that different formula brands have different rules.

Formula should be prepared once the parent or caregiver has washed their hands. Formula should not be reheated in the microwave. Lastly, formula should not be diluted beyond the regular recommended amount to save on formula. Diluted formula will mean that your baby is not getting their daily nutrition.

Lastly, always check the formula box expiry date so you know how long the unopened package of formula is good until.

Left Out But Not Consumed

On average, two hours is the longest time formula that was made but not partially consumed by baby can be left out.

Left Out And Partially Consumed

On average, a bottle of formula that has been left out and partially consumed by baby is good for an hour maximum before it spoils.

Not Consumed/ Refrigerated

A bottle of formula that is made, not consumed and refrigerated can be left for baby to consume up to two days time.

Left Out/ Not Consumed or Partially Consumed/ Freezer

It is not recommended to keep a bottle of formula in the freezer whether it has not been consumed yet or the formula has been partially consumed.

How Long Does Powdered Formula Last When Opened?

When powdered formula is opened, it has a time limit of consumption. Powdered formula usually comes in a bag or a big tin for families, depending on the brand. Always be sure to check the box of the formula to know how long it is good for once opened. Generally, the expiry date is good for approximately thirty days. However, it is important to check the box each time. It can vary from brand to brand.

Periodically, formula brands may update their information. If you have thrown out the cover box, be sure to check on social media and contact the brand. Alternatively, you can call or email the formula brand just to be sure.

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

If your child started to drink their baby formula and have left it for just over an hour, the formula would be considered spoiled and should be thrown out. Alternatively, if you have made your child a bottle of formula and they have not drank it at all, then it is good up to two hours after it has made.

What happens if formula is left out too long?

If formula is left out too long and is consumed by your child, your child can get sick, It is important to know that a newborns immune system is not fully developed until the third month. If they were to get sick, it is harder to recover. With that said, we never want to take a chance on a baby drinking spoiled formula. Similarly, if formula is outdated, you can not, by any means, feed expired formula to a child, even if the expiration date is only a few days after the current date.

Can out of date formula make baby sick?

Out of date formula can make a baby sick. Since a babies immune system is not fully developed, it can be very dangerous to expose your baby to expired formula.

Symptoms of Baby Drinking Spoiled Formula

If your baby has possibly consumed expired or spoiled baby formula, they could be exhibiting some or all of these symptoms. Symptoms of baby drinking spoiled formula include but are not limited to:


Your child vomits right after ingesting the expired formula. It may be full of formula or come out chunky.


Your newborn may experience a blotchy, red rash on their body.


Your baby has a poop that is running, messy and stinks like rotten milk. Similarly, you may find a mucus like substances in the diarrhea.

Crying Loudly

Baby suddenly starts letting out loud and strenuous cries. They are in complete distress.

Stomach Pains

This is usually coupled with loud crying. Your babies stomach feels rock hard and they are going through stomach cramps, an upset stomach or a stomach in severe pain.

Baby may experience one, multiple or none of these symptoms. If your baby ingests expired or spoiled formula, call your doctor immediately.

what happens if baby drinks old formula

If you have forgotten that you have made a bottle and are worried that your baby has consumed old or spoiled formula, check out the signs a baby shows if they are sick. Secondly, know when it is okay for a baby to consume formula. Lastly, it is best to always know how long formula lasts at room temperature. Keep your baby well fed with good formula! Be sure to take your child to urgent care if they are show any of the above signs. Call the formula’s number listed on the can if you suspect your child has swallowed old formula but is showing no symptoms of illness. Call your doctor just to be safe.

Tips To Tell That Formula Has Gone Bad

Formula does have some tell tale signs to tell us if it has gone bad. If you don’t know how long formula has been out, here are some signs to show you that it has spoiled.

It’s Chunky

You know your made the perfect formula bottle, but the formula is now chunky. It is bonding together and it is filled with chunks. It may resemble spoiled milk.

The Formula Smells

Open the baby bottle and give it a sniff. Yuck! If you smell rotten milk or a putrid rotten smell, you know that formula is bad. On the outside, it looks normal and wet. It may not even look chunky, but looks are deceiving. You give it the sniff test and it fails miserably. Thankfully, you checked, though your nostrils will not thank you, your baby certainly will.

The Formula Is Pasty

The formula is developing a film or a paste around the rim of the bottle and around the rings of the bottle. It is like a light wax paper and to the touch is slimy and could fall apart in your hand. Alternatively, you may feel hard solid parts that are thin like a broken glass. It’s too old and time to toss the old formula.

These are some of the signs that formula has gone bad! Check for it if you are not one hundred percent sure that your baby is drinking newly made formula.

Can You Reheat Previously Made Formula?

Firstly, check our list of formula safe for consumption above. Does your formula bottle follow those instructions? If not, it’s time to toss out of the formula. If so, read on! Formula can be gently reheated if it is in the time frame of good formula and is not expired.

Though many magazines may recommend it is safe to microwave a bottle to reheat it, we will have to disagree. Microwaving can create an uneven heating of a baby bottle. Some of the formula may be too hot, some at room temperature and some too cold, even though you have lightly shaken the mixture.

We recommend to always test the formula before you give it to your baby for consumption. That way, you know if it is too cold or too hot to give to your baby.

How To Reheat Formula

There are many ways to reheat formula. As we stated above, we do not recommend a microwave because of its inconsistency of heating. You can use a bowl with warm water to slowly heat the bottle. Alternatively, you could slowly warm water from the stove. Be sure to monitor it constantly so it stays at a comfortable, luke warm temperature. Formula milk should be at a similar temperature to breast milk. It is what your baby’s digestive system is built to have temperature wise.

Leaving Formula Out

If you leave formula out, you risk complications and dangers. Here are examples of what may occur when you leave formula out for this number of times.

One Hour:

  • Minimal risk, but the formula may start to lose its optimal temperature.
  • Bacteria growth is unlikely to be a significant concern within this short timeframe.

Three Hours:

  • Formula left out for three hours could be at risk of bacterial contamination.
  • Bacteria can multiply rapidly at room temperature, potentially leading to digestive issues for the infant.

Six Hours:

  • Increased risk of bacterial growth, especially if the surrounding environment is warm.
  • The formula may not be safe for consumption, and there’s a higher chance of spoilage.

A Day:

  • Substantial risk of bacterial contamination and spoilage.
  • The formula should not be consumed as it may cause gastrointestinal problems or illness.

Two Days:

  • High risk of bacterial growth, spoilage, and degradation of nutritional quality.
  • The formula is likely unsafe for consumption and should be discarded.

Potential Problems:

  • Bacterial Contamination: Leaving formula at room temperature allows bacteria to multiply, leading to potential health risks for the infant.
  • Spoilage: Formula can spoil, affecting its taste, smell, and nutritional quality.
  • Nutrient Breakdown: Prolonged exposure to air and room temperature may lead to a breakdown of some nutrients in the formula.
  • Risk of Illness: Consuming formula that has been left out for an extended period increases the risk of gastrointestinal issues and illness for the infant.

It’s crucial to follow the manufacturer’s guidelines for preparing and storing formulas. If the formula has been left out for an extended period, it’s safer to discard it and prepare a fresh batch to ensure the health and well-being of the infant. Always prioritize the safety of the child when it comes to feeding practices.


Leaving baby formula for a length of time is not only a bad idea, it could be dangerous for your baby to consume. Formula is very expensive and can be tempting to give to your child, but it can be too big of a risk to take.

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