Information

The number of people suffering with allergies in the Western world seems to be increasing. In fact, it is estimated that 1 in 3 adults will develop an allergy at some time!

Here is some brief information on allergies. More information is available from your pharmacist and doctor or click on our link sites.

What is an allergy?

An allergy is an overreaction of the body’s immune system caused by irritant substances known as allergens. The body mistakenly recognises the allergen to be a threat and reacts by releasing a chemical or “antibody” called immunoglobulin E (IgE) to attack the invading allergen. This leads to blood cells releasing other chemicals, eg histamine, that produce the signs and symptoms of an allergic reaction.

What are the signs and symptoms of an allergic reaction?

The most common signs and symptoms are:

• wheezing or coughing with shortness of breath
• sneezing with blocked or runny nose
• itchy watery eyes
• itchy throat and ears
• itchy rash with red weals (a “nettle” rash)

Very rarely an allergen can cause an acute severe allergic reaction which is called anaphylaxis. This may cause sudden swelling of face and throat making breathing difficult. It is a medical emergency and usually needs immediate treatment with an adrenaline injection.

What are the most common allergens?

Almost any protein can be an allergen or irritant for someone. The three most common allergens are:

• house dust mites
• pollens
• pets

Other allergens include medicines, nickel (in costume jewellery), and foods such as milk, eggs, fish, nuts, wheat and fruit. Insect bites and stings can also cause allergic reactions and sometimes even an anaphylactic reaction.

Who can get allergies?

Some allergies are genetic, meaning that they may run in families. If at least one parent suffers with eczema, asthma or allergies, it is more likely that any children will also suffer one or more of these. It seems that the immune system of people who are predisposed to allergies has a greater tendency to produce IgE antibodies.

What can I do if I suspect I have an allergy?

If you think you have an allergy and it is causing you problems see your doctor. There are a number of tests which may help in making the diagnosis. These include:

• skin prick tests,
• blood test for specific IgE antibodies
• patch tests for skin allergy.

Skin prick tests A skin prick test measures the amount of specific IgE in the skin. A drop of the suspected allergen solution is placed on the skin which is then pricked using a small needle or lancet. A positive allergic reaction is identified by your skin becoming itchy within a few minutes and then developing an itchy weal. A number of allergens can be tested at the same time.

Blood tests A blood test measures the levels of specific IgE produced by your immune system in response to an allergen. A sample of blood is taken from a vein and sent to the laboratory. People suffering with allergies have significantly higher levels of IgE antibodies in their blood than non- allergy sufferers.

Patch test  This is a test for those suffering with contact dermatitis/eczema. A small sample of the suspected irritant substance is taped onto the skin under a small aluminium disc. Any positive reaction can take up to 72 hours to show.

Can an allergy be treated or controlled?

The best treatment for any allergy is to avoid the allergen(s) in the first instance. So, for the three commonest allergens it is important to protect yourself from the house dust mite, pollens and pets. However, this is not always possible, partly because it is not always possible to identify the allergen or there may be too many.

There are various treatments such as antihistamines which help control the problem but these do not address the cause of our confused immune system.

See our Allergy Care section for information about ways to control your allergies.

Will my child grow out of his/her allergy?

There are no guarantees, but a significant proportion of children who develop allergies do grow out of them. Some, however, will have to learn to control their allergies throughout their lives.

Last Update: 24 April 2008