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Allergies - the answers you need

by Claudine Ryan

When it comes to allergies there seem to be as many questions as there are answers. Here we ask the experts to answer five common allergy questions.

Published 25/11/2008


Whether it's sneezing, wheezing or a life-threatening closing of the airways, allergies are a major public health problem in Australia, which has one of the highest rates of allergic disease in the world.

Most experts admit there are as many questions as there are answers when it comes to allergies. While research is vital in improving the diagnosis and treatment of allergies, it can also lead to confusion, not only for only for patients, but for allergy specialists and other medical professionals.

We asked some of Australia's leading allergy experts five common questions about allergies.

Allergy or intolerance – what's the difference?

Many people use the term 'allergy' to describe a range of symptoms, but a true allergy is a very clearly defined medical condition, says Dr Ray Mullins immunologist and president of the Australasian Society of Clinical Immunology and Allergy (ASCIA).

The big difference between allergies and intolerances is that allergies affect your immune system whereas intolerances don't.

Surveys have found up to 20 per cent of Australian adults believe they have either a food allergy or intolerance, yet only 1 - 2 per cent of adults are diagnosed with a food allergy.

If you have an allergy your immune system will 'over-react' to common substances that don't bother most people, for example dust, peanuts, bee stings or pollen. (Take a look at the allergy fact file for more information on allergies).

Mullins warns it is vital for anyone who suspects they have an allergy to get a proper diagnosis, as symptoms can be easily confused with other conditions.

Both allergies and intolerances cause a whole range of similar symptoms such as itchy eyes, rashes, asthma, eczema and upset stomachs.

But allergies have clearly defined immune system reactions whereas a food intolerance can have more non-specific symptoms such as bloating, headaches and lethargy that are not immune system related, Mullins says.

"You need to sort out if this is allergy or not, you start with a story, then you can do testing," says Mullins.

"If somebody says 'my three-year-old son has a peanut butter sandwich for the first time and within half an hour had a top-to-toe rash and face swelled up and vomited and it all went away after a couple of hours' – that's an allergy until proven otherwise."

Nutritionist Rosemary Stanton agrees people are often confused between food allergies and food intolerances.

"Food allergy creates different proteins in the blood which can be detected by a blood test, even the smallest amount of the protein causes the production of the antibodies," says Stanton.

"If you have an allergy you are going to react even if exposed to a little bit of whatever it is, you will also react quickly."

However, food intolerances are more likely to be dose related, in other words, the more you eat, the worse your reaction could be.

"The only way you can diagnose food intolerance is to cut out the food to see if the symptoms disappear and then reintroduce the food and see if the symptoms reappear," Stanton says.

The best person to diagnose an allergy is a clinical immunologist or an allergy specialist, while a dietitian can help to diagnose a food intolerance.

Allergy specialists commonly use skin prick tests to make a diagnosis, although some allergies can also be diagnosed with blood tests.

There are other allergy tests available but most of these lack scientific evidence, if you're seeking an accurate diagnosis then you should take a look at ASCIA guidelines on unorthodox diagnosis and treatment of allergic conditions.

Bottom line: If you suspect you have an allergy then you need to get a referral to an allergy specialist, who can make an accurate diagnosis.


Are serious allergies on the rise?

We know allergies in general are on the rise in Australia, we have one of the highest rates of allergy in the world.

A 2007 report found 4.1 million Australians have at least one allergy. It also found allergies cost the Australian economy $7.8 billion in 2007 and if trends continue there will be a 70 per cent increase in the number of Australians with allergy by 2050.

There's been a significant increase in the number of people being diagnosed with many types of allergies in the last decade particularly eczema, hay fever, food allergy and anaphylaxis. Although the incidence of asthma has been slowly declining since the mid-1990s.

When it comes to allergies it is anaphylaxis that makes headlines. This is a life-threatening reaction with symptoms such as difficulty breathing and speaking, swelling of tongue and throat, abdominal pain and vomiting and loss of consciousness.

There are many causes of anaphylaxis, but you can usually divide those who are admitted into hospital emergency departments into four groups, says Dr Simon Brown.

Brown is associate professor of emergency medicine at Fremantle Hospital in Western Australia, he is investigating causes of anaphylaxis admissions at several hospitals around the country.

"There's a rule of quarters – one quarter are allergic to food, one quarter to insect stings, one quarter to medications and the other quarter we just don't know.

"But this can vary depending on where you live – in the country insect stings are more of a problem, whereas food allergies tend to be worse in the cities," he says.

In the last decade, hospital admissions for anaphylaxis caused by food allergy have doubled in adults and increased five-fold in children aged 0 – 4 years.

Yet death from anaphylaxis is still a very rare event, says Brown.

"Despite the anxiety in the community death, especially in the child population, is very rare, the chance of it happening is much less than that of drowning or dying in a car accident but unfortunately it always makes it into the media," he says.

"The children that die often have poorly controlled asthma, this makes them more vulnerable, as they are less able to compensate so they are more likely to have a severe reaction."

Those most likely to die from anaphylaxis are people with asthma, the elderly and those with heart conditions.

Bottom line: While the incidence of allergies is increasing in Australia, death from life-threatening cases is rare.


Will avoiding certain foods prevent allergies?

For much of the last decade many health professionals have advised that infants, toddlers, pregnant women and breastfeeding mothers should avoid certain foods deemed to be allergenic – peanuts, tree nuts, seafood, eggs and dairy – especially in families with a genetic predisposition to allergies.

But there's little evidence to support this advice and several studies have found food avoidance can increase your risk of developing a food allergy, says Mullins.

Maria Said president of Anaphylaxis Australia says parents are often so concerned about giving their children potentially allergenic foods – especially nuts – that they ignore the advice of immunologists, which is based on the latest research.

"There is so much grey area around allergy, some things have changed quite dramatically over the last 10 or 15 years, that leaves people thinking: 'Do these guys really know what they are talking about'," says Said.

"The bottom line is that we have more questions than answers when it comes to allergy and there are some different schools of thought, if you look far enough, you can find science to back differing opinions.

"This sometimes makes it really hard for the allergy sufferer because they need answers, the right answers, now."

Mullins says advice promoting dietary restriction has prompted some parents to delay the introduction of foods such as wheat, dairy, nuts and eggs until a child is well over 12 months old.

"Many immunology specialists have been giving this type of advice for years, but things have been changing in the last year or two since we realised this hasn't worked and concern has arisen that in fact it might be doing the opposite," says Mullins.

He says delaying the introduction of a certain food won't prevent a food allergy from developing – it just delays the reaction.

"If a person already has an established allergy they're going to react whether you give it to them when they're six months old, delay it to 12 months or delay it until 18 months of age.

"There's concern that if you delay the exposure you could delay the development of tolerance.

"It's fairly naive to think not giving a person a food will stop them from developing an immune response.

"In animal studies when you try to help an animal develop a tolerance you give them buckets of that sort of food, if you cut it out of their diet then you're more likely to sensitise them to certain foods rather than to help them tolerate the food," explains Mullins.

While experts don't recommend restricting a woman's diet during pregnancy and breastfeeding, or delaying introduction of food past six months in infants – they do recommended:

  • exclusive breastfeeding of babies until 4-6 months of age
  • use of hydrolysed milk formulas for babies unable to be breastfed
  • quitting smoking

Bottom line: Avoiding certain foods doesn't appear to prevent food allergy, if your child has an allergic reaction; it was going to happen and it's not your fault.


Can you grow out of an allergy?

While there's no cure for allergies it is possible to 'grow out of them'.

Associate professor Katie Allen is a paediatric gastroenterologist and allergist in the Department of Allergy and Immunology at the Royal Children's Hospital in Melbourne.

She ran an extensive longitudinal peanut allergy study, involving 260 children over a period of 10 – 12 years, and found in almost 20 per cent of cases children outgrew their allergy before turning five.

The researchers also found children with a number of different allergies, or whose reactions were more severe, were just as likely to grow out of their allergies as were those who had less severe reactions.

"So the good news is even if you have anaphylaxis you could still grow out of your allergy," Allen says.

Allen has also helped develop a test that can predict whether small children will outgrow their allergy.

"If your child came to me at 12 months of age [and I did a skin prick test] and I then redid the skin prick test at two, three and four and if I found the skin prick test went from 10 mm, 8mm, 6 mm to 2mm then I would be able to reliably tell you that your child has a good chance of growing out of peanut allergies," says Allen.

"If the size of the skin prick test had increased I would tell you that your child had a low chance of growing out of the allergies."

What you're allergic to can also give you some clues as to whether you're likely to outgrow your allergy.

Mullins says children allergic to milk and egg often outgrow their allergy by five, but 80 per cent of those with nut, seed or seafood allergies will have them for life.

Bottom line: You can outgrow an allergy – although this can take years and is often hard to predict. You should only allow qualified professionals to test to see if you're no longer allergic to certain substances.


Is there a cure?

There is no cure for allergies so the best thing you can do after being clinically diagnosed with an allergy is avoid your trigger and have an action plan for when you don't.

"If you're allergic to a certain food you avoid it, if you're allergic to bee stings then you try to make the kids wear shoes and not wear brightly coloured clothing, if you're allergic to pets then you try not to have them in your bedrooms or house if you possibly can," says Mullins.

While this sounds simple it can be very difficult for people living with allergies especially if it's your child who is allergic. But most schools and childcare centres have policies that can help to reduce your child's chance of exposure to any allergen.

If you've been diagnosed with an allergy then chances are you have an action plan – this will tell you how to manage your condition and what to do if there's a medical emergency, especially if you have anaphylaxis or asthma.

Adrenaline is essential for people with anaphylaxis, most people now use auto-injectors, which allow people to quickly inject the correct dose of adrenaline either to themselves or someone else.

For some people with allergies there is also the option of desensitisation, or immunotherapy. This involves a series of gradually increasing doses of allergen extract, given at regular intervals over an extended period of time, usually three to five years.

The idea behind immunotherapy is that it 'switches off' the allergy by altering the immune system's reaction to allergens.

It is very affective for people with stinging insect allergies, hay fever and asthma, but not so good for food allergies.

Although, if the current research is any indication, we could see a food allergy 'vaccine' within the next five to 10 years, predicts Mullins.

"There have been studies in the last couple of years of trying to desensitise to food, the data looks interesting but it's really not ready for prime time yet," he says.

While small numbers of children and adults have been desensitised, researchers aren't sure if their allergies will flare up again or whether this is a permanent cure.

Bottom line: You can't cure allergies so you need to manage your condition and avoid your triggers. Immunotherapy can help to 'switch off' some allergies.

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