NATIONWIDE — A warning for users of epi pens — Thirteen lots of Mylan's Epipen and Epipen Jr. are being voluntarily recalled by the manufacturer.

According to the FDA, the pens have a defective part that could keep them from activating.

Epipens are used to give an emergency injection of epinephrine to treat life-threatening allergic reactions.

The recalled lots were distributed between December 2015 and July 2016.

Lot numbers of the recalled devices can be found on the FDA website, FDA.gov.