If you’re wondering, “Why is there mucus in my baby’s poop?,” you’ve come to the right place. Mucus in your little one’s stool can be a natural, harmless occurrence, but it can also be a sign of illness.1,2 Frequency and amount can determine whether there’s cause for concern.2,3 Learn more about why mucus can appear in your baby’s stool, whether breastfeeding vs. formula makes a difference and when to contact your healthcare provider.

What Is Mucus and What Does it Do?

While it may be seen as gross, mucus is an essential part of many body systems.4 In the respiratory tract, mucus acts as a barrier to inhaled germs and can help protect us from respiratory illness.4 In the digestive system, mucus creates a protective barrier and natural digestive lubrication.4 In these and other ways, mucus is essential to our health and well-being.4

What Causes Mucus in Stool?

Small amounts of mucus in stool are natural, common and not a cause for concern.2,3,4 Mucus can appear in stool as a result of lubricating the intestines or as a way to remove unwanted bacteria and viruses from the digestive system.4 Greater amounts of mucus or frequent mucus in the stool can be a sign of an issue, such as diarrhea, infection or allergy.

Normal vs. Abnormal Amounts and Frequency of Mucus in Your Baby’s Stool

Generally, if you find occasional mucus in your baby’s stool, it may be within the normal range.2,4 If your baby has mucus in their stool for three poops in a row for newborns or more than two days for babies older than one month, it may be outside of the normal range.2,4

Mucus in Breastfed vs. Formula Fed Infants

There can be a difference between the amount of mucus in breastfed vs. formula-fed babies’ poop. Breastfed babies are more likely to have more frequent, looser stools, which might more often include small amounts of mucus.2 Especially in their first few months, it can be normal for many breastfed babies to have a bowel movement after each feeding.2 Formula-fed babies tend to have bowel movements that are thicker, darker in color and may contain less mucus.2

Reasons for Higher Amounts of Mucus in Baby Stool

Most of the reasons your baby may pass abnormal amounts of mucus in their stool are not cause for serious concern.2 Here are some common reasons for excess mucus in your little one’s poop:2

  • While teething, your child may be producing more saliva
  • Food allergy
  • A virus, which the mucus is working to help clear from the system and/or which may cause diarrhea
  • For breastfeeding babies, an imbalance of foremilk vs. hindmilk2

When to Check with Your Healthcare Provider

While it never hurts to check with your healthcare provider if you are concerned about your little one, we recommend giving your health care provider a call if you encounter any of these symptoms or signs:2

  • For babies one month old or younger, three or more bouts of diarrhea including mucus or unusually foul-smelling poop lasting more than two days
  • For babies older than one month old, if mucus continues for more than two days
  • Blood in stool
  • Your baby seems to be in distress or dehydrated
  • Bowel movements seem to cause pain or distress (though signs of exertion without pain are normal, especially at three months old and up)
  • Diarrhea accompanied by fever
  • Diarrhea accompanied by vomiting
  • Poor weight gain

Rest assured that if you encounter occasional and minimal mucus in your little one’s diaper, it’s most likely part of healthy digestion. If you see it more frequently or accompanied by other signs of infection or distress, please reach out to your medical provider. To learn more about supporting the health and happiness of your little one, see our Tips and Resources.