EpiPens still potent 4 years after expiration date, study says

( CNN) EpiPen produces can still hand an effective dose long after they have expired, according to a study publicized Monday.

The active ingredient in auto-injectors like the EpiPen is epinephrine, more commonly known as adrenaline, a hormone that can be used unwind muscles. It can open airways and reduce swelling during a serious allergic reaction.

The price of the auto-injection inventions has gone up 400% since 2007, outlining the ire of patients who rely on them to quickly bar life-threatening reactions. Fury thrived as more assurance providers declined coverage of the EpiPen.