I apologize if this is a gross question. If one happens to gather saliva in the mouth on a fast day and swallows it, does it break the fast? I don’t think it was to quench thirst–more just because my mouth was dry and it was an automatic response–but perhaps it was a way to quench thirst. Is this a problem?
Thank you for your question.
Don’t be concerned with this. Swallowing saliva is not done to, and doesn’t quench one’s thirst. Additionally since the saliva didn’t leave the person’s body it is still considered part of the person and isn’t considered drinking. This according to most poskim applies to all fasts, including Yom Kippur, Tisha B’av and all other fasts.
M:B 567-13, Aruch Hashulchan 567-4, Daas Torah 567-3.