Is vomit najis?

What the schools say

• Hanafi: a mouthful of vomit is impure; a small amount is not.
• Shafi'i and Hanbali: vomit is impure because it has come from the stomach and changed.
• Maliki: it's impure only if it has changed from food, for example in smell or colour. If food comes straight back up unchanged, it's pure.
• Minority view: some scholars, such as Ibn Hazm and ash-Shawkani, said there's no clear proof that vomit is impure.

In practice, if vomit gets on your clothes or body, wash it off before you pray. That satisfies every view.

Does vomiting break wudu?

This is a separate question. Abu ad-Darda reported that the Prophet ﷺ vomited and then made wudu (Jami' at-Tirmidhi 87). The Hanafis say a mouthful of vomit breaks wudu, and the Hanbalis say a large amount does. The Malikis and Shafi'is say it doesn't, and understand the hadith as the Prophet ﷺ choosing to refresh himself. Renewing your wudu after being sick is a good idea either way. See What breaks wudu?

Babies and spit-up

For parents, especially new mothers, small spit-up is part of every day. Many scholars excuse small amounts of a baby's milky spit-up on your clothes, since washing every drop would be a real hardship. Allah says:

If a big spit-up soaks your top, change or rinse it if you can. If it's a small patch and you're worried, a quick wipe with a wet cloth is enough for most people. See Can I hold my baby while praying?

Cleaning it up

Wipe away what you can, then rinse the area with water. On a carpet or sofa, blot, pour a little water, and blot again until the smell and colour are gone. A normal washing machine cycle cleans clothes. If a faint mark remains after proper washing, it's fine to pray in it. See Can I pray with a stain on my clothes?

And if you're sick during Ramadan, vomiting that you didn't cause yourself doesn't break your fast (Sunan Abi Dawud 2380).