Australians who suffer severe allergic reactions are rolling the dice when they eat pre-packaged foods, a new study suggests.

Researchers from the Murdoch Children's Research Institute have uncovered 14 cases in Australia and New Zealand in just three months, where people suffered life-threatening anaphylaxis attacks from unlisted ingredients.

Alarmingly, half of the cases involved products that did have special allergen warnings to suggest they should be avoided.

In those cases, it's suspected the food products were contaminated with other allergens during manufacturing.

Larger studies are now being planned, with the 14 cases uncovered through surveys of medical professionals presumed to be a fraction of the real problem.

"Our study showed that anaphylaxis to undeclared allergens is not rare," says senior author Professor Katie Allen.

"The reports of anaphylactic episodes to products both with and without precautionary allergen labels is of concern. It suggests the current labelling system should be expanded to inform food-allergic consumers in safer food choices."

The study's lead author, Dr Giovanni Zurzolo, says authorities must re-examine food safety regulations, including precautionary allergen labelling, to protect vulnerable consumers.

Victorian teenager Emilia has experienced several anaphylactic attacks during her life, and carries an EpiPen with her at all times due to her severe reactions to wheat, eggs and peanuts.

Despite taking great care with her diet, she suffered an episode 18 months ago after eating a packet of rice biscuits that were in her school lunch.

"There were no ingredients listed on the label that Emi is allergic to, so we were very surprised that she had a reaction," her mother Helen Czech said.

"It is concerning that even if you read the label carefully and try to do everything right that your child could still be at risk."

The research has been published in the Journal of Paediatrics and Child Health.