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A food allergy is an allergic response to particular foods or food additives.

Eating or drinking an allergenic substance is the common cause of allergic reaction. In some highly sensitive people however, skin contact with or inhalation of allergens may cause severe symptoms. Studies show that about 6 per cent of children and 1 – 2 per cent of adults have a food allergy.

Babies and young children are most often allergic to milk, eggs, wheat, soya bean products and peanuts. Older children and adults are most often allergic to peanuts, tree nuts (walnuts, almonds and cashews), fish and shellfish. Allergies to food dyes and colours are rare.

Food allergy vs food intolerance

Many food intolerances are mistaken for allergies. A food intolerance is an adverse food-induced reaction that does not necessarily involve the immune system. Sugars and fats do not produce an allergic response. Lactose intolerance is due to difficulty digesting the sugar in milk and is also not an allergy. Food allergies do not cause hyperactivity.

Causes

Food allergy occurs when the body’s immune system over-reacts to usually harmless substances (called allergens) in some foods. Hay fever, eczema and many cases of asthma are all caused by allergies. When an allergic person comes into contact with an allergen, their immune system produces a special kind of antibody (IgE). Other cells release further chemicals such as histamine that cause the symptoms of an allergic reaction.

While allergies are not directly inherited, you may inherit a tendency to allergy, called atopy. This is called being atopic. A child with no history of allergies in the family has a 10 per cent chance of developing hay fever, food allergies, eczema or asthma. A child with one parent with allergies has a 30 per cent chance, while a child with two atopic parents has a 60 per cent. Allergies start only if you are then exposed to an allergen.

A study of more than 1000 Victorian babies has shown those with hyperactive immune cells at birth, detected in their cord blood, were more likely to develop food allergies in their first year of life. The Australian research team discovered a new pattern of immune activation at birth that was associated with an increased risk of babies developing food allergies in early life. The finding could lead to future treatments for babies and infants to prevent childhood food allergies.

Symptoms

Symptoms vary between individuals. Symptoms typically appear within minutes to two hours after the person has eaten the food to which they are allergic. The most common symptoms include:

  • Tingling sensation in the mouth
  • Swelling of the tongue and the throat
  • Difficulty swallowing and/or breathing
  • Nasal congestion
  • Runny or itchy nose (rhinitis)
  • Hives or skin rash
  • Vomiting
  • Abdominal cramps
  • Diarrhoea
  • Wheezing (this often sounds like the wheezing associated with asthma)
  • In severe cases, drop in blood pressure, loss of consciousness and respiratory failure.

Treatment

Food allergies can only be correctly diagnosed by a doctor. There is no cure for food allergies. Treatment is aimed at identifying and avoiding the trigger foods. Always check food labels carefully and do not eat anything which is unlabelled.

Your pharmacist may suggest antihistamines. Ask about any possible side effects, (eg. drowsiness).

If the allergy has caused a rash, your pharmacist may recommend an anti-inflammatory cream, such as hydrocortisone cream.

If the reaction is severe and involves difficulty breathing, rapid and widespread swelling or other symptoms it may be what is called an anaphylactic reaction and it should be treated as a medical emergency.

DISCLAIMER: This information is an educational aid only. It is not intended to replace medical advice for individual conditions or treatments. Talk to your doctor, pharmacist, nurse or naturopath before following any medical regimen to see whether it is safe and effective for you.