Video Courtesy: Bilal Naheem @ Manhaj ul-Haqq
Question: As it relates to mucus which descends from the nose to the throat, does it break the fast?
Shaykh Al Albani: Directly from the nose to the throat does not break the fast.
Question: Okay, what if they gather the mucus in their mouth (and then swallow it)?
Shaykh Al Albani: No, it has the same ruling my brother. But it is not permissible to intake mucus from an outside source, because it will then have the ruling of food and drink. And although this (swallowing mucus) is something disgusting and it is better to spit it out; but as for invalidating the fast, then it does not invalidate the fast.
Translated by Rasheed ibn Estes Barbee