ANSWER:

If you deliberately vomit, your fast is invalid. But if it was unintentional and not by choice, your fast is valid. 

Does vomit break your fast?

Fasting | May 10, 2019 9:22 am
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As Ramadan is not only about staying away from food but also staying away from uttering bad words. But what if people silently keep bad thoughts towards certain situations or people? Will their fasting be accepted?
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My board exams are being taken and my parents forbid me to fast strictly saying it’s obligatory for me to obey parents in Islam. Should I listen to them and make up the fasts later?