Baby Green Poo: Foremilk/Hindmilk & When to Worry | Parenting Hub
Baby green poo is usually harmless — fast let-down, foremilk/hindmilk imbalance, iron in formula or a tummy bug. Here's when green nappies need a GP check.
Green poo gets a lot of attention online but rarely means anything is wrong. Here's how to read what your baby's nappy is telling you.
Why poo turns green
Poo gets its colour from bile. When poo moves quickly through the gut, less time means greener colour. In healthy, growing babies, green poo is usually just a normal variation.
- Fast let-down or frequent switching between breasts (more lactose, faster transit)
- Iron in formula or infant supplements
- First poos after starting solids — especially green veg
- A mild tummy bug
- Sometimes a cow's milk protein reaction
What helps
If baby is well, you don't need to do anything.
- If breastfeeding and poos are consistently bright frothy green, let baby finish the first breast fully before offering the other
- Check formula scoops and water ratio carefully
- Watch for other clues: weight gain, feed comfort, nappy output
When to see a doctor
See your GP if green poo comes with poor weight gain, blood or mucus, persistent diarrhoea, eczema or hives, or if your baby is unsettled and uncomfortable with feeds.
When to seek urgent care
Green vomit is different from green poo and always needs urgent assessment — go to the emergency department.
When to seek help
- Green vomit (bile-stained) — emergency
- Blood or mucus in poo
- Poor weight gain or weight loss
- Persistent diarrhoea or unsettled feeding alongside green poos
Common questions
Does green poo mean a foremilk-hindmilk imbalance?
Sometimes, but this is over-diagnosed. In a thriving baby, occasional green poo is not a problem. If you're worried about milk transfer, an IBCLC can review feeds.