Affected batch numbers are 5FA665, 5FA6651, 5FA6652, and 5FA6653, all of which expire in April, 2017.

“It has been identified that EpiPens from the four affected batches may contain a defective part that could result in the auto-injector failing to activate or a need to apply more force than normal to activate,” a statement from the Therapeutic Goods Administration said. 

“If your EpiPen is from batch 5FA665, 5FA6651, 5FA6652 or 5FA6653 … return it to your pharmacy.” 

EpiPens are used to treat people who go into anaphylaxis due to severe allergic reactions.