Why was my baby’s vomit yellow?

Yellow is not one colour

We reported yellow vomit twice, weeks apart, and both times the useful part was the follow-up description.

The first time: it wasn't forceful, it just all came back out of her mouth like it didn't go down. The second: it was darker curdled milk, not actually yellow — vanilla colour yellow.

Those descriptions changed the answer entirely, and neither of them was the thing we'd been afraid of.

Curdled milk

Milk that's been sitting in the stomach meets acid and curdles. When it comes back up it looks creamy, sometimes lumpy, often described as vanilla or cream coloured.

That can be ordinary when your baby is comfortable, feeding and growing. If you are unsure whether the colour is cream or genuinely yellow, take a photo and ask rather than guessing. Formula spit-up tends to look thicker and more solid than breast milk spit-up, which catches people out after a switch.

What matters alongside it is whether she's comfortable, gaining, and otherwise herself.

The colour that doesn't wait

True yellow, yellow-green or green vomit is different. That suggests bile, which means something further down, and it needs seeing the same day rather than the next morning.

So does blood, or anything that looks like coffee grounds. So does forceful, repeated, projectile vomiting — particularly with a firm or swollen tummy, or if she's stopped passing anything.

That's not a long list, and it's worth knowing it precisely so the rest of it doesn't frighten you.

We asked about specific doses of things she'd been prescribed — how much, how often, whether an amount was safe.

That one goes to your doctor or pharmacist, every time, with her current weight. Doses for infants are weight-based and they change as she grows, so a figure that was right a month ago may not be right now.

We won't put numbers here for that reason. Ring and ask — it takes two minutes and it's the right two minutes.