Baby Accidentally Drank from Unsterilized Bottle – What Can Happen?

Balint Horvath, PhD

Writer, parent, and veteran of baby feeding battles.


If you’re a new parent you may wonder what could happen if your baby accidentally drank from an unsterilized bottle. With some parents, this has occurred and they fell into a flat panic. In this post, I explain why it’s important to sterilize baby bottles and what you can do if your baby falls ill. 

Key takeaways

  • Babies can suffer from food poisoning from an unsterilized bottle 
  • Immediately take your baby to a doctor if they fall ill from an unsterilized bottle 
  • Babies don’t always get sick from unsterilized bottles 
  • An infant’s immune system is still developing so they’re prone to getting sick 
  • Don’t reuse baby bottles without sterilizing them
  • You can use UV, steam, or microwave to sterilize bottles
  • Use a UV bag sterilizer or disposable sterilizer bags if you’re on the go

What can happen if you give a baby an unsterilized bottle? 

If you give your baby an unsterilized bottle they could fall ill with illnesses such as Gastroenteritis. This sickness can cause severe stomach ache, diarrhea and sometimes vomiting.

Another symptom that’s caused by unsterilized bottles is food poisoning from the growth of bacteria inside the bottles. Several situations can cause bacteria growth on baby bottles, like leaving milk in the bottle for too long.  

Lastly, your baby can get viral infections that can attack the liver if they drink from unsterilized bottles. 

What to do if your baby falls sick from an unsterilized baby bottle

The best thing to do if your baby falls sick from unsterilized baby bottles is to give your little one plenty of fluids. If your baby is still an infant, offer the breast or bottle more often to flush out their system. 

Make sure the room is warm or you can give your infant a warm bath which will ease aches and pains. Your baby should also get plenty of rest but it’s also important to see a doctor if the problem persists. Your doctor can provide the best remedies especially if you’re dealing with a sick newborn. 

Will your baby always get sick when drinking from unsterilized bottles? 

Your baby won’t necessarily always get sick when they drink from an unsterilized bottle but this will depend on the age of the child. There are some babies that don’t get sick at all. On the other hand, when a baby’s immune system is low, they may be more susceptible to getting sick from bottles that haven’t been sterilized. 

Why do you need to sterilize your baby bottles? 

A newborn baby’s immune system is still developing so they’re more prone to getting sick when being exposed to bacteria. Babies are extremely vulnerable to viruses and bacteria that can lead to serious illnesses. That’s why you must sterilize bottles after washing them thoroughly. 

Can you reuse baby bottles without sterilizing them?

You can let your baby feed off the same bottle if they don’t finish their formula. However, it’s recommended to throw milk out that’s been standing for more than 2 hours. Germs can grow quickly in unfinished bottles. 

Furthermore, it’s not recommended to make formula in a bottle that’s already been used. You must wash the bottle with warm soapy water and then sterilize it before using it again. 

Here’s an article I wrote on reusing the same bottle for multiple feedings.

How can you guarantee your bottles get sterilized? 

Some parents can forget to sterilize their bottles after washing them. There have also been situations where parents have forgotten to turn their sterilizers on. To guarantee that you always have sterilized bottles ready, you should set reminders on your phone. 

There are also UV sterilizers that have automatic functions. You can store your bottles in the unit and the sterilizer will switch on every hour to kill germs and bacteria living on your baby’s bottles. 

How do you properly sterilize a baby bottle? 

There is more than one way you can sterilize your baby’s bottles to ensure they are free from viruses, bacteria, and fungi. Here are methods I used regularly when my baby girl was born. 

Using a steam or UV sterilizer

There are steam and UV sterilizers on the market that are countertop units. With a steam sterilizer, you put water into the appliance which is heated up. The steam is hot enough to kill germs and bacteria. 

A UV sterilizer uses a UV-C light that breaks down chemical bonds and scrambles their DNA, protein, and RNA structures. This prevents bacteria and germs from multiplying. 

Microwave method 

Sterilizing your baby bottles using a microwave is the quickest method if you don’t have a countertop sterilizer. You also need to make sure bottles are microwave-safe. Simply pour purified water into each bottle and place it in the microwave for at least 2 minutes. The hot water and steam will kill bacteria and germs on the bottles.  

Here’s a YouTube video that shows you exactly how to sterilize your bottles using the microwave: 

A pot of boiling water 

The slowest method to sterilize your bottles is putting them into a pot of boiling water. The hot water will kill all microorganisms on the baby bottles. This method is ideal if you’re out camping because you can heat water on a gas cooker. 

How do you sterilize bottles when you’re traveling?

You can sterilize baby bottles when traveling using a portable sterilizer. There are UV bag sterilizers that allow you to store and sterilize bottles on the go. You can also use disposable sterilizing bags. 


Sterilizing your baby’s bottle is a step you don’t want to miss because it prevents your baby from getting sick. You should also sterilize your bottles more often if your baby has a low immune system. If you don’t have a sterilizer at home consider buying a safe to use second hand sterilizer to save money. 

There are other uses for a bottle sterilizer that you might find useful. Set reminders on your phone so that you never forget to sterilize your baby’s bottles.

Photo of author


I’m Balint, founder of this site and a father (and dad) to a baby-turned toddler. I found the world of babies so fascinating that I started a blog dedicated only to that topic. By the way, I studied physics, engineering (PhD, MSc), and therefore I do a thorough research when I write about something. Since it’s a blog, of course I also write about my personal experiences.

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