Her family had lived on edge for six years and watched her youngest son Isaac be hospitalised six times with life-threatening anaphylactic reactions before she decided to go against the advice of his specialists and fly to the United States to try a potential new drug-free treatment, OIT.

Fast forward nine months and Isaac, now seven, has this week returned home to Merewether, where he is eating his allergens - tree nuts, eggs and cow's milk - every day without reaction.

For the first time, he is able to eat at friends' parties, barbecues and restaurants without a second thought.

"I have a sense of calm that I did not have before," Mrs Allen said.

"The night after he graduated from OIT I slept through for the first time since he was born.

"I thought 'mission accomplished'.

"Before I was always so uptight and on edge, was always thinking the worst. The worry was just immense.

"I don't think many people realise how restrictive it is.

"One day a kid brought cashews in his lunchbox and it was like someone had brought a gun to school - this could kill my child."

The Newcastle Herald reported in January that Isaac's parents Liesel and Steven had taken Isaac - who has eosinophilic esophagitis on top of his severe allergies - last July to Dr Douglas Jones at the Rocky Mountain Allergy treatment centre in Utah to try OIT.

Dr Jones describes it as "introducing microscopic amounts of the allergen and then with a calculated, methodical approach, slowly building a person's tolerance against that allergen" until they can consume the food in unlimited amounts.

Of the more than 750 patients he has treated, 16 are Australian.

He is currently caring for a further 11 Australians.

The Australasian Society of Clinical Immunology and Allergy has warned that OIT methods are not currently standardised or approved for routine treatment of food allergy and there are concerns about a high or unknown risk of potential harm. It says avoidance is essential to manage food allergies.

"I had never disagreed with Isaac's specialists' advice, so for them to say 'No, don't go' it was a shock," Mrs Allen said.

"I cried a lot and had nightmares.

"I'm not a rebel or adventurous.

"But I felt like we had been given a life sentence and this was a pardon.

"Even if it did not work, we had to try.

"The last reaction he had at John Hunter Hospital I thought he was going to die. I thought 'If he is going to die, I want to sleep easy knowing I've done everything I could have'."

The Allens withdrew against their mortgage and ended up spending an estimated more than $100,000 on the move.

"It's absolutely worth it - it's one of the best things I've ever done," Mrs Allen said.

"It's not for everyone - we were told it would not work for us, but it has."

Isaac had to eat 24 cashews; 45 millilitres (mL) of egg white and an omelette; and 300mL of milk to be able to graduate from the OIT program, which he did many months before Dr Jones expected he would.

He may have to have his daily dose of eight cashews, 240mL of milk and 45mL of egg white - followed by a two hour rest - for the rest of his life to maintain his desensitisation.

However Dr Jones said he will continue to monitor Isaac to see if he "is a candidate to stop the daily treatment by achieving a state of 'sustained unresponsiveness'".

Mrs Allen is now on a mission to help Dr Jones make OIT available in Australia.

"It will happen, it's just a matter of when," she said. "But how many more kids have to suffer while we wait?"