Wondering what your baby's poo means? Dr Golly explains how changes in colour, texture, and frequency can indicate teething, allergies, intolerances, or dietary issues.

As a paediatrician and father of three, one of the most common questions I get from parents is: "Is this normal?" - often while referring to the contents of their baby's nappy. While it might not be the most glamorous topic, your baby’s poo can tell you a lot about their health. From teething to food intolerances, here’s how to decode what's going on.

What’s Considered “Normal” Baby Poo?

A healthy baby’s stool can vary depending on age, diet (breastfed or formula-fed), and stage of development. Colour, consistency, and frequency can all differ from one baby to another.

General guidelines:

●      Breastfed babies: Mustard yellow, seedy, soft stools

●      Formula-fed babies: Firmer, pale brown or tan stools

●      Frequency: Can range from several times a day to once every few days

Many parents worry about how often their baby poos, but, when it comes to constipation, it’s the consistency, not frequency, that matters. Some babies will poo after every feed, while others may go only once a week. As long as the stool is soft and passed without strain, this is perfectly normal.

Note: Breastfed babies are rarely constipated.

Changes in baby poo colour and consistency are often harmless, but some can signal a deeper issue.

Understanding Baby Poo Colours

Here’s a simple chart to help you decode what your baby’s poo colour might be telling you:

Poo colour/consistency	What could this baby poo mean?
Dark green or greenish black	Meconium passed in the first few days. This is your baby’s first poo and is sticky and tar-like. It is a combination of amniotic fluid, bile and fatty acids your baby ingested with still in the womb.
Pasty light brown	Normal poor for babies having formula, a peanut butter consistency.
Thick brown	Normal poo once solids begin, resembles more of an adult poo, dark brown (or darker brown then when on breastmilk or formula) and stronger smell than when just on milk feeds.
Mustard yellow	Normal breastfed-baby poo, pasty or seedy (like djon mustard). Breastfed babies can also have looser brown or green poo.
Light green	Green baby poo is normal for formula and breastfed babies, this colour poo is telling you that something has simply passed through your baby’s gut faster.   What I regularly find is a breastfeeding mother who has all of a sudden eaten a huge amount of green roughage and beans trying to fill her body with nutrition - which has made her baby’s poo green - remember what passes through your system quickly will also pass through your baby’s system quickly.
Black	Black in baby’s poo can be a sign that your baby has ingested some blood and is not normal. See your doctor if your baby has black poo. Sometimes it is swallowed blood from cracked/bleeding nipples when breastfeeding.   Note: Meconium passed in the first few days is black (very dark green) but your baby’s poo should not stay black in colour.
Red	This is not normal and could be a sign that your baby is bleeding. It can also be a sign that your baby has an intolerance. See your doctor if your baby’s poo contains blood.
White or light grey	This is not normal. This could be a sign that the liver may not be producing enough bile, making the poo white in appearance and a chalky texture. See your doctor.

 

If your baby’s stool is ever red, white, or black (after the meconium phase), it’s time to see a doctor.

Note: If your baby has started eating solid food, make a mental note when you have tried beetroot with them. This can often scare parents when it makes its way through to the nappy, appearing similar to blood, bright red!

Here are some common occurrences that can bring on changes to baby poo:

1. Teething and Poo Changes

Teething doesn’t directly cause diarrhoea, but it can lead to looser stools.

Why it happens:

●      Increased saliva production during teething affects digestion

●      Babies often chew on objects, introducing more germs

What you might notice:

●      Slightly looser stools

●      More frequent dirty nappies

●      Mild nappy rash due to increased acidity

When to seek help: If the diarrhoea is persistent, watery, or contains blood/mucus, consult your baby’s doctor.

2. Not Chewing Food Properly

As your baby transitions to solids, you might see whole or undigested food in their poo — and that’s okay!

Common culprits:

●      Corn, peas, carrots, blueberries

What it means:

●      Your baby’s digestive system is still developing

●      Their chewing skills may need time to improve

What to do:

●      Ensure foods are cut appropriately

●      Supervise mealtime

●      Encourage chewing by serving soft finger foods

●      Model adequate chewing for them

3. Food Allergies

Some stool changes may indicate a potential food allergy, particularly in response to cow’s milk, eggs, soy, or peanuts.

Signs in the nappy:

●      Blood or mucus in the stool

●      Diarrhoea or chronic constipation

●      Excessive gas or discomfort

Other symptoms:

●      Skin rashes (e.g., eczema)

●      Vomiting or feeding refusal

What to do:

●      Eliminate suspected allergens under medical supervision

●      Check with your GP or paediatrician for allergy testing as required

4. Food Intolerances

Intolerances differ from allergies. Children can be sensitive to these to begin with, but grow out of them in time.

Common signs in poo:

●      Frothy or explosive stools

●      Frequent diarrhoea

●      Greenish tinge to stool

Possible triggers:

●      Lactose (found in dairy)

●      Fructose (fruit sugars)

●      Additives or preservatives

What to do:

●      Keep a food and symptom diary

●      Trial elimination under guidance from a healthcare professional

When to Seek Medical Advice

See your GP or paediatrician if:

●      There is blood, mucus, or a foul smell

●      Your baby has a fever or is not feeding well

●      Poo is white, black (once meconium has passed), or unusually pale

●      You notice persistent diarrhoea, constipation, or pain

White, red, or black stools (after meconium stage) can indicate serious underlying issues and should always be assessed by a doctor. Mucus or blood in the poo may also point to a possible intolerance to breastmilk or formula and warrants medical review.

Final Thoughts from Dr Golly

Your baby’s poo can offer helpful clues about their digestion, development, and even early signs of intolerance or allergy. Keep an eye on any changes, but don’t panic. Most variations are completely normal. When in doubt, trust your instincts and speak to a healthcare professional if you’re worried.

As a father of 3 and paediatrician, Dr Golly has seen his fair share of dirty nappies. His first book, ‘Your Baby Doesn’t Come with a Book, Dr Golly’s Guide to the First Four Weeks of Parenthood’ covers common newborn poo colours and consistencies. His second book ‘Dr Golly’s Guide to Family Illness, Sneezes, Wheezes and Common Diseases’ covers all common paediatric nappy issues.

For more baby health advice, including expert help with baby sleep, visit drgolly.com.