A shortage of life-saving EpiPen devices for young children has seen experts recommend the use of out-of-date stock or devices containing adult doses to treat severe allergic reactions.

Across the country, pharmacists are experiencing a short-term shortage of EpiPen Junior devices - adrenaline auto-injectors used to treat life-threatening symptoms of anaphylaxis that can prevent death and brain damage.

The shortage means it is not possible for parents and carers to buy replacements for expired devices or those due to expire during November.

In a statement, Mylan Australia, which distributes the EpiPen products, said the shortage was due to a delay in supply from the overseas manufacturer.

To bridge the gap, the company is offering eligible patients a free EpiPen Jr, but those devices will expire on November 30.

Pharmacists and allergy specialists say there are other options available for those whose auto-injectors have expired.

'No harm in using expired EpiPens'

"When patients and family members come in seeking stock, our advice to them is if they have an out-of-date or expired pen at home, providing it's not discoloured, they can still use that," pharmacist Anthony Tassone told RN Breakfast.

Mr Tassone, who is Victorian president of the Pharmacy Guild of Australia, said his two pharmacies had been out of stock of the devices for some time, and he was hearing many other pharmacies in cities and across regional Australia were also affected by the shortage.

Professor Katie Allen, a paediatric allergist based at Murdoch Institute, said there was no harm in using expired EpiPens.

"The issue about an expired EpiPen is that the adrenaline's efficiency is decaying with time," she said.

"There's no doubt that manufacturers are going to have a buffer zone in there because they can't afford to get it wrong. So it might be weeks or months before it starts to decay."

Professor Allen said it was likely the devices would still be effective several weeks after they expire.

Adult EpiPens also an option for some children

Professor Allen said children weighing more than 20 kilograms were also able to use 300 microgram or adult-dose EpiPens.

"In fact, the Australian Society of Clinical Immunology and Allergy recommend you can have a full-strength EpiPen when you reach 20 kilograms," she said.

"They could get it slightly earlier, even if someone is 19 kilograms I would just give them a 300 microgram one because they are going to grow in the next few months anyway."

There is also another product available, Professor Allen said, but it's rarely prescribed and if you want more information you should speak to your doctor.

Pharmacists still in the dark

Mr Tassone said it was still unclear how long it would take for the EpiPen Jr devices to be supplied to pharmacies, and he criticised the time it had taken for Mylan to communicate about the back-up product.

"I only heard of that late yesterday afternoon and it was as a result of media inquiries that I heard," he said on Thursday.

"The Australian public is feeling like they're being let down. Health professionals are also feeling like they're in the dark about being kept up to date with the stock shortages.

"More needs to be done to make sure that we do have adequate stock, that shortages are being reported appropriately, urgently and in a timely way."

Stock of the EpiPen Jr product, which is recommended for people weighing 10-20kg, is expected to be available again in mid to late November.