Young mother feeding baby girl in living room, what to do if baby drinks spoiled breast milk
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What Happens If Your Baby Drinks Spoiled Breast Milk?

Experts explain what to do if it happens, and how to prevent it.

by Mishal Ali Zafar
Originally Published: 

Storing breast milk is something most breastfeeding parents have to deal with, regardless of whether they’re pumping all the time or just building up an emergency stash. But if you didn’t notice that the milk you spent so much time pumping and storing going bad, it can lead to some major headaches. The good news is, if you follow proper storing guidelines, you shouldn’t really encounter this problem. But in the case that it does, can your baby get sick from drinking spoiled breast milk? Here’s what the experts want you to know.

What happens if a baby drinks spoiled breast milk?

If you’ve unknowingly fed spoiled breast milk to your baby, Hawaii-based International Board Certified Lactation Consultant (IBCLC) Deborah Dominici says they will likely throw it up, if not immediately spit it out. “Very rarely will milk spoil if you follow proper breast milk handling and storage guidelines,” Dominici tells Romper. “But occasionally it happens and, generally, the result will be vomiting up the spoiled milk.”

The biggest risk when it comes to spoiled breast milk is exposing the baby to a contaminant that has grown. “Spoiled breast milk may contain bacteria, which could be harmful to your baby or make them sick,” Dr. Mona Amin, a board-certified pediatrician, tells Romper.

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Just because your little one accidentally drank and spit up spoiled breast milk doesn’t necessarily mean they will get sick. But remember, babies are still building their immune systems and are thus more susceptible to illnesses. You’ll know if your baby is sick from harmful bacteria based on the symptoms they exhibit after drinking the milk. “With spoiled breast milk, the main concern is bacteria harboring together,” Amin says. “Any unusual symptoms will warrant a call to your child’s medical provider, including high fever, extreme fussiness, or excessive vomiting.”

How long does it take them to get sick from spoiled milk?

Essentially what your baby is dealing with if they get sick from spoiled breast milk is food poisoning. “How long it takes for a baby to get sick on spoiled breast milk depends on the circumstances, including how much was consumed and the state of the spoiled milk,” Amin says. “Depending on the amount, you may want to monitor for symptoms at home or call your medical provider.”

Signs of food poisoning in babies

If your baby immediately spits out the milk, then you probably won’t have to deal with any issues. If they do consume spoiled breast milk, however, there’s a possibility that they will show signs of food poisoning, such as vomiting, diarrhea, low-grade fever, and an overall upset stomach. Like other foodborne illnesses, symptoms will likely show up in 2 to 48 hours. Sometimes it will resolve on its own with time and fluids (read: water), but if their symptoms are not getting better after a day, they are throwing up excessively, or they have a fever above 101 degrees, definitely contact a medical provider for personalized care.

Signs of spoiled breast milk

The first thing to do is to figure out if your breast milk has actually gone bad. “The smell and taste will be indicators of spoiled milk,” Amin says. Common signs that breast milk is spoiled, according to Amin, include:

  • A sour smell
  • An odor like rotten fish
  • A smell or taste that is ‘off’ in any noticeable way

It’s also helpful to think about where, when, and how the milk has been stored when gauging if it has gone off or not. “If you can, you should also keep track of how long your milk has been out at room temperature, how long it has been in the fridge, and how long it has been in the freezer,” Amin says. “If the milk is freshly expressed or pumped and it’s been sitting at room temperature for longer than four hours, throw it out.”

Sometimes parents may see their breast milk separating, but as Dominici explains, that fat separation in breast milk is completely normal and not an indicator your milk has gone bad. that Sometimes, when a breastfeeding parent has higher lipase in their milk, and when the frozen breast milk is defrosted, it could have a soapy or metallic smell, but it would still be safe to give to a baby, Dominici says.

How to store breast milk and prevent it from spoiling

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There are lots of steps you can take to make sure your milk doesn't go bad. Human milk is a living fluid, with antimicrobial agents that keep it fresh and safe to consume after pumping, but unless you follow proper breast milk storage guidelines it could go bad, explains Danielle Spradlin, IBCLC of Oasis Lactation Services.

“The best way to prevent milk from going bad is to store it properly and use clean, sterile storage containers (glass or plastic) and secure it properly with a lid/top of some sort,” Dr. Amin says. “Freshly expressed or pumped milk can be stored at room temperature for no longer than four hours, in the refrigerator for no longer than four days and in the freezer for six months to one year.”

How you handle your milk makes a difference, too. In addition to storing your milk in clean containers, Spradlin advises pumping with a properly cleaned pump to maintain fresh milk. She explains that cases of babies getting sick from pumped milk are usually due to cross contamination, which can occur when a caregiver is preparing a bottle while also preparing foods with a contaminant (like salmonella or E. coli), which is why good hand hygiene is incredibly important. “We forget that common objects we touch like computers, cell phones, diaper bags, and pump bags are not clean,” Spradlin says, “and sometimes these items sit on the floor or in the floors of our cars.” Hand contamination is the easiest contamination to control, she notes, by just washing your hands well before pumping.

Seeing your baby squirm or reject your milk should be the first signs to stop feeding it to them. For the most part, babies will probably let you know if it the milk tastes bad by refusing it and spitting it out. If you’re worried that your child has ingested spoiled breast milk, call your pediatrician or health care provider for guidance.


Dr. Dr. Mona Amin, DO, FAAP, board certified pediatrician

Deborah Dominici, RN, IBCLC, International Board Certified Lactation Consultant

Danielle Spradlin, IBCLC, International Board Certified Lactation Consultant of Oasis Lactation Services

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