If he vomits unintentionally and he is overwhelmed by it, it doesn’t affect his fasting. Only when he deliberately vomits that it nullifies his fasting.
The Prophet (salla Allahu alahi wa sallam) said: “The one who cannot help vomiting does not have to make up the fast, but the one who vomits deliberately has to make it up.” Classed as saheeh by al-Albaani in Saheeh al-Tirmidhi.

And Allah knows best

Someone told me to ask u this question,actually this person is suffering from ulcer and he has to take medicines and he gets vomiting while he is fasting so in that condition is it premissible for him to fast?

Fasting | March 30, 2014 5:57 pm
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I heard that first we should keep fast for the days which we missed in ramadan then 6 days of shawwal so is it must to keep first missed days of ramadan then 6 days of shawwal please clarify it sheikh..
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If the women wear the proper hijab,or niqab and after prayer she go back home and try to avoid mixing with man even in streat..can she pray in the masjed?