Issur to Eat before Kiddush
Friday Night Kiddush
17. One may not eat or drink anything before Kiddush, not even water (שו''ע או''ח סי' רע''א ס''ד). Once Shabbos arrives and it might be considered night or if one took in Shabbos even by day, the chiyuv of Kiddush takes effect and he may not even taste something (מ''ב סקי''א) even if he did not yet daven Maariv (ערוך השלחן סי''ב).
18. Ill, pregnant. If a woman took in Shabbos by lighting candles before bein hashmashos and is very thirsty for water, e.g., she is pregnant or nursing, she may be meikel and drink water as long as it is before shekiyah. This is because she is considered to be in a situation of discomfort and she cannot make Kiddush (מהרש''ם, קונטרס אהבת שלום אות י''א בסוף ספר מנחת שבת).
19. Nevertheless, it is better for her to make Kiddush for herself and eat a bit of bread to fulfill Kiddush in the place of the seudah, as it is rare that a woman is unable to make Kiddush (שו''ת מנח''י ח''ח סי ' ח"י). She should certainly make Kiddush and eat if it is already after shekiyah. [At the night Kiddush, one should not suffice with eating mezonos if it is not a pressing situation (שו"ת עין יצחק או''ח י''ב) or with drinking a revi’is of wine (שע ה"צ רע''ג סקכ''ט) to fulfill Kiddush in the place of the seudah.]
20. Obviously, if someone desperately needs something, not mere thirst, and there is a possibility of fainting ch”v, he/she may certainly eat or drink even without making Kiddush.
21. Medicine. One may rinse his mouth with water before Kiddush since the intent is not to enjoy the taste (מ''ב סקי''ג). One may also take a pill for health reasons that is permissible on Shabbos with a bit of water before Kiddush since he does not derive enjoyment from the water (שו''ת מנח''י שם, מו''ר בשו''ת שבט הקהתי ח''א סי' צ''ו וק''ט).
22. Children. Children, even if they are chinuch-aged, may eat something small before Kiddush – Chazal did not make a gezeirah against something that is for the benefit of a child (מג''א סי' רס''ט סק''א).
23. Thus, children may eat candy they get in shul; the ones who distribute the candy do not transgress the issur of feeding a child issur (מג''א שם). Nevertheless, if it is age-appropriate, one should train them to wait until after they hear Kiddush (אור לציון ח''ב פמ''ז אות ו').
