Turns out granddad's breakfast of peanut butter on toast four hours prior had been enough to trigger a severe allergic reaction.

Callan, now three, had reacted to foods containing peanuts previously but the reaction from such a slight trace of the nut from another person, indicated a severe food allergy.

"When he was 12 months we gave him a peanut butter sandwich and he went red in the face, and then again at 18 months he had a reaction to some satay," Mrs Lawrie said.

"But after the incident with his grandfather we went to see an allergist who confirmed that he had a severe, life-threatening, allergy to all nuts as well as eggs and sesame."

The couple have since banned nuts from their household and have educated their family and friends as well as Callan's pre-school. They are also supporting a new awareness campaign, Raise Your Hand for Anaphylaxis, which was launched this month.

Around 4.1 million Australians suffer from at least one allergy and campaign ambassador Dr Andrew Rochford said everyone needed to be aware of allergies and how to identify symptoms of anaphylaxis.

"We need to ask ourselves, would I know what to do if I or someone else has an anaphylactic reaction? In this type of emergency, every minute counts," Dr Rochford said.

"Anaphylaxis awareness is crucial, especially in schools. This campaign will be offering teachers, students and all Australians the opportunity to learn more about allergies in a very practical way."

Ms Lawrie said it was an important campaign for schools, with more and more students being diagnosed with severe allergies and having to take allergy medication with them to school.

"Families like ours need more people to be aware and not just assume that we are 'new age' over-protective parents that want to control what our kids eat.

"Callan's allergies are life-threatening - we could lose him if we don't keep on top of this - but we know many people still don't understand that."

Callan was too young to fully understand what he could and couldn't eat and how severe his reactions could be, "so the more adults in the community who are aware the better", Ms Lawrie said.

For more information on the campaign visit www.anaphylaxis101.com.au.