All perfect praise be to Allah, The Lord of the Worlds. I testify that there is none worthy of worship except Allah, and that Muhammad is His slave and Messenger.
It seems most likely that Asthma spray spoils fasting since it reaches the throat, and consequently without any doubt, it reaches the stomach.
Therefore, if a fasting person needs to use it, he should break the fast like any patient who eats or drinks medicine. Later, he should make up all the days he missed fasting. Our opinion is based on the statements of scholars which clearly state that any material that reaches the throat is similar to that which reaches the stomach; and every material that reaches the stomach intentionally invalidates the fasting.
Allah knows best.