In the scene right before the kids go into the grave to get 'it', they all take a hit of the inhaler. When it's the girl's turn, she inhales but she forgot to hit the button.
You're really not supposed to take a hit on someone else's inhaler if you're not asthmatic. I'm not sure if anything happens though. I've never seen what happens though, if anything.
when i was in grade school i took a hit off someones inhaler after running (i wanted to see if it woould help stop my heavy breathing) and i dont have asthma. nothing happened. i dont even think it helped my breathing.