Short answer

• If you are fasting and you vomit unintentionally, the fast is generally NOT broken. You may continue, but do not swallow anything after vomiting. Rinse your mouth and rest.
• If, to manage vomiting, you swallow any outside substance (water beyond your pachchakhana, ORS, medicine, clove, etc.), the fast is considered broken.

Details with Jain tradition in mind

• What keeps the fast: Vomit that is only your own body’s bile/saliva or previously‑allowed boiled water coming out does not count as “new intake.” Spit it out fully, rinse without swallowing, and you may continue the fast.
• What breaks the fast: Swallowing any new edible/liquid/medicine after the vomiting.
• Health first: If weakness, dehydration, or dizziness continues, end the fast respectfully. Do alochanā/pratikraman and, if you wish, take a new pachchakhana for a lighter vrata (e.g., boiled‑water only, ekāsan) when health permits. Ahimsā includes care of your own body.

Notes by tradition

• Shvetāmbara (many communities): Upvās usually allows only boiled, filtered water during daylight. Vomiting itself does not break the fast; swallowing any new substance does. You can, with fresh pachchakhana, shift to “boiled‑water only” if unwell.
• Digambara (stricter on water): Upvās commonly means nothing by mouth (including water). If you must take water/medicine due to sickness, the upvās ends; do pratyākhyān and take a lighter tapa when fit.

Practical steps now 1) After vomiting, spit out completely and rinse without swallowing. 2) Sit/lie down; if you feel stable, you may continue the same fast. 3) If unwell, respectfully end the fast, take needed care, and later resume with a suitable vow.

Related simple guides

• Upvās with only boiled water and sample pachchakhana:
• Timing of water in tivihār upvās: