Your question: I have a Ventolin inhaler, but it is expired. I got it last year, and the expiration date says September 2013. I have not used it for about a year now. Should i use it?
Expired asthma medicines are still safe to use, it's more that the chemical composition starts to break down over time, making them less effective (time may also make them taste funny).
I would advise going ahead and using it if you need it, because if you need it and it works, great. In the meantime, I would make efforts to get a new inhaler. Once you get a new inhaler, I'd discard the old one.
On a side note, I would recommend getting a new inhaler, whether you use the old one or not, every six months. This way, even if one becomes expired, you will still have one that is fresh and ready to go.
This will definitely cost a bit more to do it this way (about $40 a year), but when you are having an asthma attack you will thank yourself.
Any further questions please let me know.