Short answer
No. Brushing your teeth does not break the fast as long as you swallow nothing. In the Hanafi school a miswak is sunnah at any time of the fasting day, while toothpaste and mouthwash are makruh (disliked) because of their taste, and swallowing any of them breaks the fast.
Using a miswak, or a toothbrush with plain water, is sunnah and allowed all day, before and after midday. Toothpaste and mouthwash are makruh tanzihi without need; if any of it goes down the throat, the fast is broken and one day of qada (make-up) is due, with no kaffarah.
Other madhhabs
- Shafi'i
- Using a miswak after midday (zawal) is makruh for the fasting person, so as not to remove the smell of the fasting mouth that the hadith praises.
- Hanbali
- The main view of the school also dislikes the miswak after midday for the fasting person.
Explanation
The fast is broken by something reaching the throat or stomach through the mouth or another open passage. A toothbrush only touches the teeth and gums, so brushing in itself does not affect the fast. The only concern is what you might swallow.
Miswak and a dry brush. The Prophet ﷺ urged the miswak with every prayer and did not exclude the days of fasting, which include Dhuhr and Asr. For this reason the Hanafi scholars hold that it is sunnah all day long for the fasting person, whether the stick is dry or fresh. A toothbrush used with plain water takes the same ruling. Spit out the water well afterwards.
Toothpaste and mouthwash. These have a strong taste and are easy to swallow by accident, so Hanafi muftis class them as makruh tanzihi (mildly disliked) during the fasting hours. The fast stays valid if you rinse and spit carefully. If some paste or mouthwash slips down your throat, the fast is broken even though it was an accident, and you make up one day.
- Best practice: brush with toothpaste at suhoor and after iftar.
- During the day: use a miswak, or a brush with water only.
- A minty taste left in the mouth after spitting does not break the fast.
- Bleeding gums: spit the blood out. See does bleeding break your fast.
For the full list of what does and does not break the fast, use the what breaks your fast checker.
The evidence
Quran, Surah Al-Baqara 2:187
أُحِلَّ لَكُمْ لَيْلَةَ ٱلصِّيَامِ ٱلرَّفَثُ إِلَىٰ نِسَآئِكُمْ ۚ هُنَّ لِبَاسٌۭ لَّكُمْ وَأَنتُمْ لِبَاسٌۭ لَّهُنَّ ۗ عَلِمَ ٱللَّهُ أَنَّكُمْ كُنتُمْ تَخْتَانُونَ أَنفُسَكُمْ فَتَابَ عَلَيْكُمْ وَعَفَا عَنكُمْ ۖ فَٱلْـَٰٔنَ بَٰشِرُوهُنَّ وَٱبْتَغُوا۟ مَا كَتَبَ ٱللَّهُ لَكُمْ ۚ وَكُلُوا۟ وَٱشْرَبُوا۟ حَتَّىٰ يَتَبَيَّنَ لَكُمُ ٱلْخَيْطُ ٱلْأَبْيَضُ مِنَ ٱلْخَيْطِ ٱلْأَسْوَدِ مِنَ ٱلْفَجْرِ ۖ ثُمَّ أَتِمُّوا۟ ٱلصِّيَامَ إِلَى ٱلَّيْلِ ۚ وَلَا تُبَٰشِرُوهُنَّ وَأَنتُمْ عَٰكِفُونَ فِى ٱلْمَسَٰجِدِ ۗ تِلْكَ حُدُودُ ٱللَّهِ فَلَا تَقْرَبُوهَا ۗ كَذَٰلِكَ يُبَيِّنُ ٱللَّهُ ءَايَٰتِهِۦ لِلنَّاسِ لَعَلَّهُمْ يَتَّقُونَ ﴿١٨٧﴾
It has been made permissible for you the night preceding fasting to go to your wives [for sexual relations]. They are clothing for you and you are clothing for them. Allah knows that you used to deceive yourselves, so He accepted your repentance and forgave you. So now, have relations with them and seek that which Allah has decreed for you. And eat and drink until the white thread of dawn becomes distinct to you from the black thread [of night]. Then complete the fast until the sunset. And do not have relations with them as long as you are staying for worship in the mosques. These are the limits [set by] Allah, so do not approach them. Thus does Allah make clear His ordinances to the people that they may become righteous.
The fast is defined as holding back from eating, drinking and intercourse from dawn to sunset, and brushing is none of these.
Sahih al-Bukhari 887
Sahih... لولا أن أشق على أمتي لأمرتهم بالسواك مع كل صلاة ...
"Were it not that it would be hard on my community, I would have ordered them to use the miswak with every prayer."
The encouragement covers every prayer, including those that fall during the fasting day.
Where the ruling is recorded
- al-Hidaya, Kitab al-Sawm, chapter on what requires qada and kaffarah. There is no harm in the fasting person using a fresh miswak, morning or evening.
- Radd al-Muhtar (Ibn Abidin), Kitab al-Sawm, chapter on what breaks the fast and what does not. The miswak is not disliked at any time; tasting or chewing something without need is makruh.
- Fatawa Mahmudiyya, Kitab al-Sawm. Toothpaste during the fast is makruh, and the fast breaks if any of it is swallowed.
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.