People with EpiPens are being urged to check them to see if they need to be swapped after a defect was found in certain batches.

Four batches of life-saving EpiPens are being recalled after they were found to possibly contain a defect that could prevent them from injecting properly.

EpiPens are used in emergency situations to treat people who are having severe allergic reactions.

If they don't activate properly, there is a risk a patient may not receive the required dose of adrenaline in a timely manner or they may not get the dose at all.

The Therapeutic Goods Administration is urging people with the EpiPen 300 microgram adrenaline injection syringe auto-injectors to check the batch number and expiry date on either its label of the end of the carton.

Those from batches 5FA665, 5FA6651, 5FA6652 and 5FA6653, all expiring in April 2017, should return them to any pharmacy to swap for one from a different batch for free.

The TGA has confirmed two reports of auto-injectors from these batches failing to activate correctly, out of about 80,000 devices distributed worldwide.

No other batches of EpiPen, including the EpiPen Jr 150 microgram version, are thought to be affected, the TGA said.