Baby Poop Smells Like Vinegar – Is There Something Wrong?

By Maria Wilcox •  Updated: 06/09/22 •  10 min read
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Sometimes as parents, we run into situations with our babies that leave us scratching our heads. If you’ve noticed that your baby poop smells like vinegar, it may have left you wondering what’s up. Though strange and unusual, baby poop that smells like vinegar can have both benign and alarming causes. In this post, we will detail most reasons this occurs as well as give you information on what you can do to help remedy it. If this sounds interesting to you then be sure to stick around…we’re getting started right now! 

What Does It Mean When Baby Poop Smells Like Vinegar?

Baby poop can take on all sorts of unusual smells. But baby poop that smells like vinegar should alert you that something is up.

While this sort of smell may mean nothing at all, it is always a good idea to speak with your pediatrician as to why this is happening especially when it is paired with other symptoms. 

For now, let’s explore some of the common reasons that vinegar-smelling baby poop happens in the first place:


Malabsorption is a term used to refer to the body’s inability to absorb macro- and/or micronutrients for the nourishment of the body. There can be several reasons for malabsorption, including damage to the intestines, lactose intolerance, irregularities present at birth, and a plethora of other things.

Malabsorption may present itself as light, bulky, or oily stools, a distended stomach, belly pain, and diaper rash. And yes, vinegary or otherwise very smelly stools. 

Allergies or Sensitivity to Certain Foods

Lactose intolerancefood sensitivities, and allergies can also cause vinegar-smelling stools. If your baby is sensitive to certain types of foods or has trouble digesting dairy products, it may be that you notice that his or her stools smell like vinegar along with constipation, abdominal cramping, rash (in the diaper or around the mouth), or excess mucus. 


Some parents have noticed vinegar-smelling stools crop up whenever their child starts teething. Because teething can cause your baby to swallow an excessive amount of saliva and can cause digestive issues, it is possible that teething could be the cause of unusual-smelling stools.

Sometimes, the smelly stools can be linked to baby ibuprofen often administered to help with pain relief as this may be hard on your child’s tummy.

Rather than administer ibuprofen when your baby is too young, you may consider relieving your child’s tooth pain by giving him or her naturally-derived teething toys to chew on instead. It can also help if you chill these for added relief!

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Sensitivity to Mother’s Diet

When breastfeeding, it is imperative that mothers are mindful of what they eat. Some foods from the mother’s diet can make it into the mother’s milk. Therefore, they inadvertently affect the baby.

Certain food like broccoli, beans, and milk are known to cause upset stomachs in newborns as their bodies learn to adjust. As such, sensitivity to foods in mom’s diet can lead to vinegar-smelling poop.

Sensitivity to Baby Formula

On the other hand, babies that consume formula may be reacting poorly to their formula. As a result, may have vinegar-smelling poop.

If you’ve recently started giving your baby formula or have recently switched formulas, you may wish to consult your pediatrician with your concerns to evaluate whether or not there may be a better formula option out there for your baby. 

Crohn’s Disease

Crohn’s Disease is an illness that inflames the bowels and causes soreness in the digestive tract. It is often accompanied by foul-smelling stool, abdominal cramping, and bleeding from the rectum. 


Rotavirus is a disease that can cause watery stools, dehydration, and vomiting, most commonly in children under the age of 5.

If you notice these symptoms along with vinegar-smelling stools, it may be a cue that it is time to give your pediatrician a visit. 

Cystic Fibrosis

Cystic Fibrosis is a disorder that causes damage to the lungs and organs as the body secretes mucus and digestive juices that are thick and sticky that thereby can cause a multitude of issues.

One of the symptoms of cystic fibrosis can be fatty and smelly stools.

why does baby poop smell sour

What Causes Sour Smelling Poop?

Why Baby Poop Smells Like Vinegar?

As previously mentioned, sour-smelling poop can have multiple causes, stemming from an inability to properly digest foods down to diseases involving indigestion and inflammation.

We recommend seeing a doctor if you notice vinegar-smelling poop paired with other alarming symptoms such as abdominal cramping, bloody stools, fever, rash, or vomiting. 

When Should I Worry About Baby Poop Smell?

A baby’s poop can take on a variety of colors, textures, and smells.

However, there are times when baby poop should be considered abnormal. Anytime your baby’s poop veers from the norm, you should take notice. A vinegary or fishy smell paired with fat in the stool, blood in the stool, or unusual colors may be cause for concern, especially if it happens consistently. 

Know that black poop is common in newborns a few days old, yellow poop is common in breastfed babies, and earth-toned colored or green poop is frequent in formula-fed and older babies. Colors that span outside of these may be cause for concern especially if paired with an unusual odor.

Speak with your doctor for more details. 

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Breastfed Baby Poop Smells Like Vinegar

Breastfed Baby Poop Smells Sour

Remember that breastfed baby poop can take on a variety of odd characteristics. Especially when your baby is allergic or has a sensitivity to things you’ve been eating.

As a breastfeeding mother, you’ll need to be very careful what you consume, especially while your newborn is young. Some foods may cause your baby to have an upset stomach which could result in unusually smelly stools. 

Foods that may (or may not) cause your baby issues include:

  • Dairy
  • Beans
  • Broccoli
  • Corn
  • Cabbage
  • Cauliflower 
  • Citrus
person carrying baby in arms

Formula Fed Baby Poop Smells Like Vinegar

Remember that babies often have sensitivity to cow’s milk or other ingredients in baby formula and that not every formula is the same as the next. Some babies tolerate some formulas better than others.

It is important that you speak with your pediatrician concerning which formula might work best for your baby to eliminate strong or vinegar-smelling feces. 

Baby Poop Smells Like Vinegar Teething

Teething can sometimes cause your baby to experience digestion issues as they swallow excess saliva and gnaw on a variety of things to get relief.

Instead of giving your baby ibuprofen before he or she is able to handle it, it may be better to seek other remedies like gum massagers or textured teething toys. Eventually, the vinegar-smelling stool associated with teething should pass, but if it doesn’t, be sure to give your pediatrician a call.

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Baby Poop Smells Like Vinegar and Green

Baby poop can take on a variety of colors and scents, but green poop isn’t normally something to worry about.

Green poop is common in breastfed babies and in babies that are eating solids, especially if your baby has been eating foods that are green.

As mentioned, however, the vinegar smell may be tied to an internal issue or may be linked to digestive problems, so if it continues and your baby seems to be in pain or is having other concerning symptoms, be sure to pay your baby’s doctor a visit. 

1 Year Old Poop Smells Like Vinegar

6 Month Old Baby Poop Smells Like Vinegar

Babies aged 6 months to 1 year may have vinegar-smelling poop associated with new foods added to their diet. Unless there are other symptoms present, vinegar-smelling poop for babies that are trying new foods may not be something to worry about.

If, however, this kind of poop is also tied to diarrhea, vomiting, constipation, bleeding, or other issues, you’ll want to have your baby get checked out right away. 


Why does my newborn smell like vinegar?

Sometimes it is sweat, breath, or poo that can smell like vinegar in newborn babies. Additionally, if your baby has been drinking milk that has made its way into your baby’s neck folds, you could begin to notice that your baby smells particularly sour. To prevent this, always wash your baby’s neck folds, and try to bathe your baby regularly to keep strange smells emitting from the body at bay. Vinegar smells coming from a baby’s breath may be indicative of something more serious, so be sure to seek a doctor’s advice. 

Why does my baby’s poop smell like ammonia?

A diaper that is drenched and mixed with stool and urine for much too long can cause a strong ammonia smell that may even eat away at your baby’s skin. Always change your baby’s diaper on time, and never allow your baby to sit in a heavily soiled diaper, especially after your baby poops.

mom and child photo

Baby Poop Smells Like Vinegar? Pay Attention…

While there are plenty of innocent reasons why your baby’s poop could be smelling like vinegar, the truth is that a persistent odor like this in a baby’s stool may not be good, especially when paired with other symptoms.

Be sure to write down what you notice and present it to your pediatrician to get tailored advice concerning the health of your child. 

More reading about poopy odors:

Maria Wilcox

Former instructor with an M.A. in Education turned grateful stay-at-home mama to one, I look to share helpful insights related to babies, toddlers, kids, and families for the benefit of real people just like you.

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