Allergy and Chemical

Know the signs of food allergy and sensitivity and what you can do to help reduce the risk.

This page has been written exclusively for by Sue Ellis (BSc Clinical Psych, M Ed). Sue Ellis has 25 years experience as a psychologist and has a special interest in chemical sensitivity and behavioural problems in children. She is currently living and working in Melbourne.

After the sheltered environment of the womb, the newborn child discovers a world full of exciting and rich experiences. However these new experiences are also sometimes stressful. Many sources of stress are environmental – traffic, noise, over-stimulation from TV, the hustle bustle of modern family life, pollution to name a few. Although a certain amount of stress is healthy some researchers believe that too much stress or certain types of stress can affect the immune system and may have a key role in the development of allergy and chemical sensitivity.

The number of children effected by allergy and chemical sensitivity has risen dramatically over the last decade and there is increasing concern that the widespread use of pesticides and hormones in farming as well as the use of additives in food processing may be largely to blame. Infections from bacteria and viruses can also be a source of stress and have also been linked to the onset of health problems associated with chemical sensitivity.

Symptoms of allergy and chemical sensitivity can be physical or behavioural and are often chronic. Physical problems include hayfever, eczema, asthma, rhinitis (runny nose) and lethargy. In cases of severe allergy there can be problems with breathing which can be life threatening. Behavioural problems include hyperactivity, mood swings and difficulty with concentration.

While there is a great deal of controversy about the effect of artificial colours and flavours on childhood behaviour, research carried out over 20 years at the Royal Alfred Hospital Allergy Unit in Sydney has produced results that are even more controversial. That is natural chemicals in food can cause more problems than additives. The results of this study involved about 20,000 patients who were seen at the clinic and form the basis of a book called Friendly Food (1991) by Swain, Soutter and Loblay, which is available from most bookshops. This article is largely based on their findings.

What is the difference between an allergy and chemical sensitivity?

There is a great deal of confusion about allergy and chemical sensitivity, many people think that they are the same thing. However different biological pathways and processes are involved and there are different approaches to prevention and treatment.

Both allergy and chemical sensitivity can be a problem in childhood – some children will have problems with one or the other, whereas other children will have problems with both allergy and chemical sensitivity:


Allergic reactions are triggered by the immune system. The body sometimes mistakenly perceives a substance, which is not normally harmful, as a threat. When this happens the immune system goes on triple alert and antibodies are created to destroy the substance, which is called an allergen. If this is unsuccessful, special cells called mast cells, produce anti-histamine to try and immobilize the allergen, causing the allergic reaction.

Allergens are often environmental, for example dust mite droppings, medication, pollens and insect stings. However protein molecules in food can also be allergens. The most common food allergens are proteins found in egg, wheat and milk. Less commonly fish and nuts, especially peanuts, can be a problem. Allergy symptoms are usually triggered immediately or within a few hours and severe reactions can often be linked to something that has just been eaten. The most common symptoms of allergy in children are swelling and itching especially around the mouth, cramps, vomiting, diarrhoea, and skin conditions such as eczema.

In extreme cases of allergic response there may be difficulty with breathing – anaphylactic shock – that can be life threatening. Hence it is essential that all allergy tests be carried out in a doctor’s surgery under the supervision of an allergy specialist as even the smallest amount of allergen can trigger an extreme response in some children. Your specialist will also help you determine whether there is another underlying cause that may also need to be treated. Luckily true allergy is not common as only about 5% of children under 5 develop an allergy.

How do I know if my child has an allergy?

There is no definitive test for allergy. The most reliable test is the RAST blood test that measures the IgE or antibody response to particular allergens and the skin prick test. Although these tests are not 100% accurate other tests are even more unreliable and have little scientific validity.

What can I do if my child has an allergy?

If your child has an allergy it is necessary to avoid the allergen completely until such time as he or she grows out of it.


Josh has a severe allergy to peanuts. This means that he must completely avoid peanuts and commercial products that may have traces of peanuts in them, for example chocolate and some snack foods.

Josh also suffers from asthma. The results of a RAST and skin prick test suggested he was allergic to dust mite. In fact it is not the dust mite itself but the dust mite droppings, which can trigger asthma and eczema, in an allergic child.

In Josh’s case, as there is no definitive test for allergy, his family had to dust and vacuum regularly to see if his symptoms improved. It was also important to reduce clutter and surfaces that attract dust such as ornaments, curtains and carpets – luckily they had polished floorboards and tiles that are more easily cleaned. His mother also covered Josh’s bedding with approved covers for mattresses, pillows and doonas, designed to prevent dust mite droppings from coming into contact with Josh while he was in bed.

Cats, in particular, can cause problems, as they tend to leave fur on carpet and furnishings. Cat fur is a common source of dust particles and skin flakes that can also be a problem, so Josh’s cat, Treacle, also had to be given a new basket – outside on the back porch. Josh’s symptoms improved dramatically after a few weeks that demonstrated that in his case dust mite was a source of stress that could trigger an asthma attack.

Fortunately most, but not all, children grow out of their allergy by the time they reach school age.

Can I prevent my child from developing an allergy?

Even if you have no allergies this is no guarantee that your child won’t develop an allergy, however, your child has a slightly higher chance of developing an allergy if there is a family history of allergy or a sibling with allergies.

Did you know that:

  • Dietary changes commencing in the second half of pregnancy and continuing during breastfeeding may be helpful in reducing the risk of your child developing an allergy
  • It is important to eat a balanced diet without bingeing on any one food as some mothers report that their child developed an allergy to foods they had strong cravings for in the second half of pregnancy.
  • Nuts can cause lifelong problems, so total avoidance of nuts and nut traces, often found in chocolate, is recommended up to about 15 months even in children who skin tested negative to nuts before this age.
  • Children who skin test negative to milk after 6 months can usually be safely weaned on to milk.

These and other tips are outlined in Prevention of Food Allergy by Valencia Soutter and is available from the Royal Prince Alfred Allergy Unit in Sydney.

Chemical Sensitivity

Chemical sensitivity is less easily understood than allergy and is thought to be mediated by neurological pathways involving receptor cells on nerve endings. Both natural and artificial chemicals in food can trigger symptoms of chemical sensitivity, also referred to as food intolerance. Surprisingly, Loblay, Soutter and Swain (1991) at the Royal Prince Alfred Allergy Unit found that naturally occurring chemicals, including amines (often found in tasty foods such as cheese and tomatoes), salicylates (often found in aromatic foods such as fruit and spices) and glutamate (flavour enhancers) are more often the culprit in food intolerance, than artificial additives.

Some foods have more than one chemical in them.

Chemical sensitivity is also not as easily diagnosed as allergy and symptoms often flare up after a rich or spicy meal. Hence parents often wrongly assume a particular food in the previous meal has been the cause. However this is rarely the case as has been demonstrated by Loblay, Soutter and Swain. They explain that the effects of chemical sensitivity are cumulative and dose related. In other words, symptoms don’t occur until the chemicals have built up to a certain level, or threshold, in the body, usually over a number of days. Children with chemical sensitivity often react to more than one chemical, natural or artificial or both, and the effects of these chemicals are cumulative making it difficult to pinpoint which chemicals are to blame.

Symptoms can have pharmacological effects, similar to the side effects of drugs, including headache, tiredness and muscular aches and pains. Chronic hives and gastrointestinal problems can also occur. In some instances asthma attacks have been triggered by sensitivity to sulphite preservatives (an artificial additive) or, less frequently, naturally occurring salicylates.
Sensitivity to monosodium glutamate or MSG, a flavour enhancer, often added to Chinese food as soy sauce or as a pure white powder, has also been found to sometimes trigger an asthma attack, occasionally with fatal consequences.

There is increasing evidence that chemical sensitivity can also cause behavioural problems such as hyperactivity and irritability. These problems can also be associated with attention problems in some children. In recent years many such children have been diagnosed with Attention Deficit/Hyperactivity Disorder or ADHD and the use of stimulant medication, such as Ritalin, to treat ADHD is now widespread.

Unfortunately the role of naturally occurring chemicals in causing chronic symptoms is often unrecognized. However many parents have found a significant relationship between chemical sensitivity, to both natural and artificial chemicals, and their child’s physical and behaviour problems and report dramatic improvements once the offending chemicals are eliminated from their child’s diet.

How do I know if my child has a chemical sensitivity?

The most reliable method for identifying chemical sensitivity is to do an elimination diet under the supervision of an appropriately qualified dietitian. This means restricting the diet to foods that are very low in natural chemicals and additives, including preservatives, flavours and colours. The diet is usually carried out for 2-6 weeks. If at the end of that time, there is no improvement in symptoms, it is unlikely that chemical sensitivity is a factor. If on the other hand there is an improvement in symptoms then a series of challenges are carried out, usually over a month or two. People with chemical sensitivities often report a worsening of symptoms and cravings for foods rich in the offending chemicals in the first week of the elimination diet. This is because of pharmacological effects described as being similar to drug addiction withdrawal. Subsequent exposure is characterized by an acute sensitivity to these chemicals once they are no longer in one’s system.

Common Parental Myths

"My daughter breaks out in hives when she drinks orange juice".

"Milk makes my son blocked up and gives him a runny nose"

Parents with a child who has chronic problems such as skin rashes, rhinitis (a constantly runny nose not due to infection) and even asthma often notice a significant improvement when their child is taken off particular foods, such as sugar, dairy, wheat, or citrus. As a result it is commonly thought that these foods cause the problem.

However fruit contains a natural preservative called salicylate that can cause problems for sensitive children. Similarly, bread and dairy products are often combined with fillings or sauces rich in amines, another naturally occurring chemical found in foods such as cheese, tomatoes and chocolate.

Most fruit juice is high in naturally occurring salicylates and some fruit juice, such as orange juice is high in both salicylates and amines and also often contains preservatives. MSG, often added to snack food, is also a naturally occurring chemical which is found in some fruits – including tomatoes, plums, grapes and sultanas – and vegetables – including mushroom, broccoli and spinach.

"My daughter becomes hyperactive if she has too much sugar"

"My son becomes argumentative and has temper tantrums when he has lollies"

Children’s behaviour often improves on a diet free of sugar and artificial additives, however, this can be because many foods containing sugar, artificial colours and flavours, are also high in natural chemicals such as salicylates and MSG.

What can I do if my child has a chemical sensitivity?

If your child has a chemical sensitivity it is important to establish what your child’s threshold is for the offending chemicals and make sure that the amount of chemicals in the diet does not exceed this threshold. This is often a matter of trial and error and parents are advised to seek advice from a registered dietitian who is trained in this approach. After a period of time children, and adults, often lose their sensitivity and foods containing these chemicals can then gradually be increased.


Sally was 11 years old when she suddenly developed chronic hives. Her hives were so bad, causing large, itchy red welts all over her back, stomach and sometimes on her legs and arms – even in her armpits, both during the day and at night, that she had to take antihistamines daily for relief. Sally’s mother took her to a dietitian who put her on an elimination diet. After 2 weeks Sally’s hives were greatly improved and she was able to go off the antihistamines. Challenges showed that she was extremely sensitive to salicylates. Sally had to stay on foods low in salicylate, but was able to reintroduce foods high in other natural chemicals such as amines, back into her diet. After six months it was possible to gradually increase her intake of salicylates without her hives worsening. Sally was also sensitive to some environmental triggers that also contain salicylates, such as perfume, and cleaning agents, which meant that it was also important to try and reduce her exposure to these things as much as possible.

Can I prevent my child from developing a chemical sensitivity?

A chemical sensitivity can develop at any age. One risk factor is bingeing on particular foods. Hence a commonsense approach is recommended. That is try to encourage your child to eat as wide a variety of foods as possible and rotate foods each day rather than eating the same foods every day. In other words food fads should be discouraged in order to minimize the risk of developing a chemical sensitivity further down the track.

Where to find further information:

Friendly Food, (1991), Dr A. R. Swain, Dr V. L. Soutter and Dr R. H. Loblay, Allergy Unit, Royal Prince Alfred Hospital (available from most bookshops)
Prevention of Food Allergy, Valencia Soutter, Royal Prince Alfred Allergy Unit
Fed Up (1998), Sue Dengate, Random House.


Names in this article are fictitious and any resemblance of case histories to real people is coincidental.  

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