9 Reasons Why Your Baby’s Poop Smells Like Vinegar

baby poop smells like vinegar

During the first few weeks of motherhood, the emotional pendulum swings wildly from euphoric highs to blistering lows.

Between hormones, lack of sleep, and that new, tiny human in your home, it can all be so overwhelming. Of all the bizarre things that you find yourself doing as a new parent, studying the contents of dirty diapers as if preparing for a dissertation on baby poop, might top the list.

A few days after our first daughter’s arrival, I noticed something strange when I changed her diaper. Which is saying something, since the first few diapers in the hospital are filled with a ghastly, black, tar-like substance called meconium. Totally normal for a baby’s first poop, it turns out, but nonetheless jarring.

No, this was different. I’d been prepared (as much as one can be) for the meconium diapers, but I wasn’t ready for the watery, yellow, seedy-like substance that I was now wiping from my daughter’s tiny bottom. My horror grew as she continued to double down on this new consistency of baby poop.

On the ninth day, I was in a blind panic. Certain she had diarrhea and was terribly ill, I made an appointment with our pediatrician. With shaking hands and a lump in my throat, I described my daughter’s affliction. She smiled and cast a pitying sort of look at me and said kindly, “That’s a healthy, breastfed baby poop.” Relief flooded me as I sunk into the chair and sobbed.

As strange as it may seem, monitoring your baby’s bowel movements can be very informative. It can let you know that your baby is healthy and everything is normal and it can alert you that something is wrong.


Is It Bad if Your Baby’s Poop Smells Like Vinegar? 

Normal, breastfed baby poop is usually yellow and seedy and has a sweet smell. Much like I described in the story above. It can be just as important to know what’s normal for your baby and might just save you from a teary pediatrician visit.

As the infant continues to nurse, it’s not uncommon for a baby to go a day or two without a bowel movement. Most of the nutrients in breast milk are absorbed, which leads to fewer dirty diapers.

Formula-fed baby poop smells a little worse and is often larger. They are sometimes solid and typically have the consistency of peanut butter.

As babies grow, are exposed to the environment, and begin eating solid foods, there can be changes in their poop. You may notice a difference in odor or consistency and wonder if you should worry.

One of the most common concerns is when a baby’s poop smells like vinegar. There are reasons for sour-smelling stool, ranging in severity from mild to serious. Let’s take a look at the potential causes, what you can do about it, and when to call the pediatrician.


9 Reasons Why Your Baby’s Poop Smells Like Vinegar

1. Teething

While there is no science behind this possible culprit, teething is often accompanied by watery stools, gas, and bloating. Many parents have noticed that after a few days of sour-smelling stools, a new tooth surfaces.

2. Lactose intolerance

Babies can react to the dairy in the formula as well as any milk products that mom consumes and passes through breast milk. It can result in painful gas, bloating, and diarrhea.

3. Food allergies 

Once you start introducing solid foods to your baby’s diet, it will most certainly change her digestion. If your baby is allergic to any foods, it can cause stools to smell more acidic in nature.

4. Food sensitivity 

Some babies are sensitive to certain foods and they can be hard on their digestive system and result in foul-smelling poop. Occasionally, this can produce mucus or even blood in the stool.

5. Change in diet

Any change in your child’s diet will likely result in a change in his poop, sometimes causing a sour smell. If you’re nursing and make changes to your diet, this can affect the baby. If a formula-fed baby changes formula, this can cause changes as well.

6. Malabsorption

When your baby isn’t absorbing the nutrients in her digestive tract, it can cause the poop to have a vinegar smell or even to be white in color. Malabsorption can happen because of a virus, parasite, infection, or other disorders and can sometimes lead to dehydration.

7. Microflora imbalance in the gut

Microflora is good bacteria in the gut and is essential for healthy digestion.

Babies who are born vaginally, naturally receive good bacteria. When they pass from the safety of the womb and amniotic fluid through the birth canal, they receive a whole new microbiome.

Babies born via C-section don’t get the same benefits and can result in an imbalance in that good gut bacteria. When that imbalance happens for any reason, your baby’s poop can have an acidic smell.

8. Rotavirus

Common in babies due to its high contagion level, rotavirus is a nasty virus that causes symptoms such as fever, vomiting, and watery stools that have a putrid smell, and those stools can sometimes contain blood or pus.

9. Crohn’s disease

Crohn’s disease is a serious illness that can cause explosive, watery diarrhea that has a particularly sour smell. Stools may also contain blood or mucus.


9 Potential Remedies to Get Things Back to Normal

1. For teething…

Gas drops, teething gel, and massaging your baby’s gums can help some symptoms, but time is the only cure.

2. For lactose intolerance…

If you suspect that lactose intolerance could be the source of the problem, try a formula made without dairy or eliminate dairy from your diet if you’re nursing.

3. For food allergies…

Be sure to monitor new foods you introduce so that you can correlate them with any new diaper smells or other symptoms you might notice. If there is any family history of food allergies, it’s good to be extra cautious. If you think food allergies are at play, it’s important to call the pediatrician.

4. For food sensitivity…

Food sensitivity can range from annoying to serious. If you notice symptoms such as blood or mucus in the stool, it’s time to call the doctor.

5. For a change in diet…

Sudden changes in diet can cause an upset tummy. While momentarily uncomfortable, the situation typically resolves itself as your baby grows accustomed to the changes or you return to your original diet or baby’s original formula.

6. For malabsorption…

In some cases malabsorption can be serious, leading to dehydration and other problems. It’s important to monitor your child and call a doctor if symptoms last longer than a few days

7. For microflora imbalance in the gut…

Pediatric health dietitian, Melinda Braithwaite suggests some ways to improve your baby’s gut health here. One of her recommendations is to breastfeed for as long as possible.

8. For Rotavirus…

Getting enough fluids is essential to your child’s health. Since rotavirus can cause dehydration, be sure to call the pediatrician if symptoms don’t resolve in a few days.

9. For Crohn’s Disease…

It’s important to seek medical attention if you think Crohn’s disease could be the cause.

Those dirty diapers can tell us a lot about what’s going on inside your baby’s little body. Sometimes when your baby’s poop smells like vinegar, it’s nothing more than teething or something you ate before breastfeeding. Other times it can signify something far more serious.

Monitoring your baby’s health means monitoring their poop. Being aware of the warning signs can go a long way in knowing when to make changes at home and when to call the pediatrician.


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