Answered by Shaykh Amjad Rasheed
Is it permissible for a person to rinse out his mouth to reduce the dryness of his mouth, especially in hot countries?
Yes, it is permissible. But, he should be careful about any water reaching his body cavity, for that would break his fast, even if he doesn’t exaggerate in his rinsing, because this is an action that is not required.
[Translated by Sr. Shazia Ahmad]