Shaykh Muqbil explains that using a siwak (toothstick) during fasting is permissible, even if green. However, toothpaste should be avoided in Ramadan to prevent the risk of swallowing it. There is no clear evidence that toothpaste breaks the fast, but caution is recommended.
What is the ruling on using the (siwāk) toothstick and toothpaste while fasting?
In regards to using the (siwāk) toothstick from the al-Arāk [tree] then there is no problem with it, even if it is green. As for using toothpaste, then we advise abandoning it in Ramaḍān, and we do not have any proof to say it nullifies the fast. So it is obligatory that he makes sure nothing enters his stomach.
Indeed the Prophet ﷺ said, “Sniff water into the nose excessively [in wudu], unless you are fasting.”
