Mucus in baby poo – should I be worried?

Your baby’s stool (poo) will differ depending on what they are fed. The stool of breastfed baby will look a little different to that of a baby who is formula fed. A baby who has started solids will have different stool to a baby who is still being exclusively milk fed. If your baby is exclusively fed breast milk, their poo will most likely be quite watery and a mustardy-yellow colour. If your baby is formula fed, their poo will likely be thicker in texture and might resemble the colour of peanut butter. When your baby starts solids, their bowel motions usually become less frequent initially, and you might notice surprising colours or undigested parts of food in their poo.

Understandably, you might be concerned if you notice a small amount of mucus in your baby’s nappy. Mucus can make your baby’s poo seem shiny, slimy, or even jelly-like. If your baby is otherwise well, seeing small and infrequent amounts of mucus in your baby’s poo is usually not a cause for concern and no further treatment is required. Mucus is naturally produced in the intestine and helps stools to move through the gut effectively.  However, if your baby has frequent or very large amounts of mucus in their poo, it might indicate an underlying condition.

Some conditions commonly associated with mucus in the stool are:


Teething causes excess saliva in the mouth. Sometimes the increased amount of saliva causes drooling, while other times it enters the digestive tract, irritating the gut and resulting in mucus in the stools.

Gastroenteritis (gastro) or other viral infections

Gastro is a highly contagious viral infection that can cause vomiting and/or diarrhea in babies, children and adults. Gastro can cause inflammation in the gut which may lead to mucus in the stool. Other viral infections, including the common cold, cause extra mucus production in the body, which can lead to mucus in the stool. This should usually pass as other viral symptoms improve.

Intolerances or allergies

Repeated exposure to a food intolerance or allergen can result in chronic inflammation in the gastro-intestinal tract, which can result in mucousy stools. According to Melbourne based pediatrician Dr. Daniel Golshevsky, mucousy stools can be a sign your baby is reacting to something in your breast milk or the formula they are being fed. One of the most common intolerances in babies is Cow’s Milk Protein Intolerance (CMPI). You can read more about this in Willby’s blog: Allergies and intolerances in babies.


This is a condition where part of the intestine slides into another part of the intestine (sometimes called telescoping). This can cause blood and mucous in the stool and is a serious condition that requires immediate medical attention.

In any case of mucousy stools, the treatment is dependent on the cause. If you notice mucus in your baby’s stool, monitor their nappies closely and keep a record of the frequency and duration. You might even want to take some pictures of the contents of your babies nappy, as this can be helpful to healthcare providers in diagnosing conditions associated with mucousy stools.

If you baby has additional symptoms such as a fever, lethargy, or inconsolable crying or fussing, see you family doctor for advice.

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