I just went for a breathing test cause ive had a cough for over 6 months was wondering if i could take a puff of my mom blue inhaler would it hurt me?

Hard to say: If you are very lucky it would do nothing bad. If the true cause of your condition is a fungus & your blue inhaler is a steroid you could make the condition worse. Self medication with drugs is a dangerous path to be on. If they were meant for self dx/use they would be available over the counter.

Bad idea: You should never use medication prescribed for someone else.