Can I use a miswak while fasting?

What the Prophet ﷺ did

A miswak (also called a siwak) is a small twig from the Arak tree, used to clean the teeth. Amir ibn Rabi'ah said he saw the Prophet ﷺ using the siwak while he was fasting more times than he could count (Jami at-Tirmidhi 725). The Prophet ﷺ also encouraged it in general, saying that if it were not hard on his followers, he would have ordered them to use it at every prayer (Sahih al-Bukhari 887). Nothing in these reports limits it to certain hours of the day.

If you are new to the miswak, see What is a miswak and do I have to use it?

What about the afternoon?

Some people hesitate because of the saying of the Prophet ﷺ that the smell coming out of the mouth of a fasting person is better in the sight of Allah than the smell of musk (Sahih al-Bukhari 1894). This leads to a small difference between scholars:

• Hanafi and Maliki schools: using a miswak is fine at any time of the fasting day.
• Shafi'i school: it is mildly disliked (makruh) after the sun passes midday, so that the breath of the fasting person is not removed.
• Others: many scholars today point out that the Prophet's ﷺ regular use of the siwak is clear, and that the hadith about musk praises the reward of fasting, not bad breath.

So you are on safe ground whichever view you follow. If you want to keep it simple, use it after suhoor and before Dhuhr, and rely on this as a gentle rule of thumb rather than an obligation.

How to use it so your fast stays valid

• Use a clean stick with a freshly trimmed end.
• Spit out any saliva with a woody or bitter taste instead of swallowing it on purpose.
• Don't swallow pieces of the fiber.
• Go gently if you are using a moist or flavored miswak, as the taste can linger.
• Don't worry if a trace of taste is in your mouth. Only deliberate swallowing matters.

Brushing is also fine if you take care not to swallow water or toothpaste. See Can I brush my teeth while fasting? and Can I use mouthwash while fasting?

A sunnah that freshens your breath

A miswak is a simple, cheap way to look after your mouth in Ramadan, and it helps with the dry-mouth taste many people notice in the afternoon. For why a fasting person's breath is honored, see Why does a fasting person's breath smell good to Allah?