Dr. Muzammil Siddiqi, former president of the ISNA and member of the Fiqh Council of North America, answers: “The use of an inhaler during fasting is permissible because the inhaler only provides some moisture; it doesn’t involve the taking in of any liquid or food through the mouth. Even when we take a breath, we take in some moisture into our throats and that doesn’t break our fast. Therefore, in any similar way, the use of an inhaler is permissible.”
The late Saudi scholar Sheikh Abdul-`Azeez Ibn Baz (may Allah bless his soul), said in one of his fatwas:
“The use of inhaler is permissible in case of necessity, based on the verse: “… and He has already made plain to you what He has forbidden to you– excepting what you are compelled to…” (Al-An`am 119)
It is also permissible because it does not resemble food or drink; it is similar to undergoing a blood test or taking non-nutritional injections.”