What happens if someone is using an asthma inhaler, without asthma?

Should be fine: A one time accidental use would probably not result in any side effects. One use an inhaled steroid would cause negligible side effects. Using a bronchodilator, like albuterol, may cause one to get jittery. If one is concerned about adverse reaction then it would be appropriate to seek medical care.

Kill you !!!: Any med that is strong enough to do good can hurt you if you use it wrong.I recall a runway model who found she could suppress her appetite by using her inhaler.She died of an overdose when her heart developed an irregular heartbeat.This is occasionally prescribed in non asthmatics and is fine is used as directed. Self prescribing & use is dangerous.