What is the ruling on a fasting person using an inhaler for breathing problems, and does it break the fast?
This spray is vaporised and does not reach the stomach, so in that case, we say that there is no objection to using it when you are fasting, and it will not cause you to break your fast, because as we have said, none of its particles enter the stomach. Since it is something that is defused and vaporised, and it disappears, then none of it reaches the stomach, therefore it is permissible for you to use it when you are fasting and the fast is not invalidated by it.
Shaykh Muhammad bin Saalih al-`Uthaymeen
Fatawa Arkaanul-Islaam, DARUSSALAM, Vol.2, p.658