Why Is My Baby's Poo Green?

Here's when you actually need to worry.
Mother changing twin babies diaper at home
Viktor Cvetkovic via Getty Images
Mother changing twin babies diaper at home

Baby poo comes in a range of different colours, when they’re born, for the first few days it’s often black which is called meconium.

This is made up of materials ingested in the womb and is a sign their bowels are working properly and typically clears within 2-4 days.

Once you start breast feeding, physician Dr Naheed Ali and medical writer for Sweat Block explains that poo will become mustard yellow in colour and have a seedy, mushy texture. The smell is usually mild, and it’s normal for breastfed babies to poop after every feed.

Why is my baby’s poo green?

Though it’s easy to worry when you see a sudden change in your child’s poo, rest assured green poo is pretty normal!

In fact, it could be down to changes in lifestyle for your baby. Formula-fed babies tend to have firmer, darker brown or greenish stools compared to breastfed babies, and the smell is also usually a bit more pungent.

Dr Ali says: “There are a bunch of reasons why baby poop turns green! Most of the time, it’s completely normal. Think about what you’ve been eating if you’re breastfeeding (lots of spinach?), if your little one has started solids, or if either of you are taking iron supplements.

“Sometimes, getting too much foremilk or a little tummy bug can also turn things green for a while.

Even a change in formula brand can lead to a shift in poo colour, including grey and green tones. This is completely normal, explains Dr Ali.

“Because different formulas have slightly varying compositions of nutrients, vitamins, and minerals. Your baby’s digestive system is simply adjusting to this new formula,” he adds.

As long as the poo consistency is normal (not watery or hard) and your child isn’t showing signs of discomfort there’s no need to worry.

Once your child’s body gets used to the new formula, their poo colour will likely return to its usual shade within a few days.

“Typically, green poop alone isn’t anything to stress about. However, if the poop also has blood or mucus in it, your baby has persistent diarrhoea, or seems extra fussy, it’s definitely worth giving your paediatrician a call. They can help figure out if it’s just a phase or something that needs a little extra attention.

“Remember, every baby is different, so paying attention to what’s normal for YOUR little one is key!”

When should I be concerned?

Though some variation in colour and consistency is normal, there are a few signs that could indicate an issue like diarrhoea, constipation, or an allergy, says Dr Ali.

He says the signs to look out for are:

  • Poo that is very pale, chalky, or clay-coloured
  • Black, tarry stools (after the newborn stage)
  • Red or bright red streaks
  • Constipation lasting more than a few days
  • Diarrhoea (having multiple very watery stools in a short period)

If you are worried, Dr Ali says to contact your GP.

“Otherwise, trust your instincts as a parent! Getting familiar with what’s normal for your little one’s dirty diapers goes a long way in catching any issues early,” he says.