Short answer
No. Swallowing your own saliva never breaks the fast, and in the Hanafi school swallowing phlegm or mucus that comes down from your head or chest does not break it either, though spitting it out is better. Swallowing someone else's saliva, or saliva with a lot of blood in it, does break the fast.
Your own saliva is excused, even if you swallow a lot of it. Phlegm or nasal mucus that comes into the mouth and is swallowed does not break the fast according to Abu Hanifa and Muhammad, which is the relied-upon view, but spitting it out is better. Deliberately gathering saliva in the mouth and then swallowing it is makruh but does not break the fast.
Other madhhabs
- Shafi'i
- Phlegm that reaches the front of the mouth and is then swallowed on purpose breaks the fast; if it goes down before reaching there, it does not.
- Hanbali
- Swallowing phlegm after it has reached the mouth breaks the fast in the main view of the school.
Explanation
Saliva is produced all day and no one can avoid swallowing it. Allah does not burden a soul beyond what it can bear, so swallowing your own saliva has no effect on the fast at all, whether it is a little or a lot.
Mucus and phlegm. With a cold, hay fever or post-nasal drip, mucus often runs down the back of the throat. In the Hanafi school this does not break the fast, because it comes from inside the body and is hard to avoid. If it has reached your mouth and you can spit it out easily, spit it out: that is the better and safer choice, and it also avoids the difference with the Shafi'i and Hanbali schools.
What does break the fast:
- Swallowing another person's saliva, for example while kissing.
- Swallowing saliva mixed with blood when the blood is equal to or more than the saliva, or you can taste it.
- Saliva that has fully left the mouth, such as a drop that fell onto your hand, and is then taken back in.
Do not let this become a source of worry. You do not need to keep spitting all day, and a fast is not broken by doubts. If waswasa (persistent intrusive doubts) about saliva troubles you, see the what breaks your fast checker and speak to a scholar you trust.
The evidence
Quran, Surah Al-Baqara 2:286
لَا يُكَلِّفُ ٱللَّهُ نَفْسًا إِلَّا وُسْعَهَا ۚ لَهَا مَا كَسَبَتْ وَعَلَيْهَا مَا ٱكْتَسَبَتْ ۗ رَبَّنَا لَا تُؤَاخِذْنَآ إِن نَّسِينَآ أَوْ أَخْطَأْنَا ۚ رَبَّنَا وَلَا تَحْمِلْ عَلَيْنَآ إِصْرًۭا كَمَا حَمَلْتَهُۥ عَلَى ٱلَّذِينَ مِن قَبْلِنَا ۚ رَبَّنَا وَلَا تُحَمِّلْنَا مَا لَا طَاقَةَ لَنَا بِهِۦ ۖ وَٱعْفُ عَنَّا وَٱغْفِرْ لَنَا وَٱرْحَمْنَآ ۚ أَنتَ مَوْلَىٰنَا فَٱنصُرْنَا عَلَى ٱلْقَوْمِ ٱلْكَٰفِرِينَ ﴿٢٨٦﴾
Allah does not charge a soul except [with that within] its capacity. It will have [the consequence of] what [good] it has gained, and it will bear [the consequence of] what [evil] it has earned. "Our Lord, do not impose blame upon us if we have forgotten or erred. Our Lord, and lay not upon us a burden like that which You laid upon those before us. Our Lord, and burden us not with that which we have no ability to bear. And pardon us; and forgive us; and have mercy upon us. You are our protector, so give us victory over the disbelieving people."
What cannot be avoided, like swallowing one's own saliva, is not held against the fasting person.
Where the ruling is recorded
- al-Fatawa al-Hindiyya, Kitab al-Sawm, chapter on what breaks the fast and what does not. Swallowing one's own saliva does not break the fast; phlegm drawn from the head into the throat does not break it according to Abu Hanifa and Muhammad.
- Radd al-Muhtar (Ibn Abidin), Kitab al-Sawm, chapter on what breaks the fast and what does not. Blood mixed with saliva breaks the fast when it equals or exceeds the saliva.
- al-Majmu' (Nawawi), Kitab al-Siyam. The Shafi'i distinction between phlegm that reaches the outer mouth and phlegm that does not.
This answer is pending review by the scholars on our team. Quran translation by Sahih International. Hadith Arabic from the standard editions of the six books and the Muwatta, with gradings as recorded there; the English is our own rendering. Spotted a mistake? Tell us.