An allergy is an abnormal reaction to protein substances, which are found all around us. When a person with an allergy is exposed to these substances or allergens, the body prepares to fight back. The blood cells produce an antibody against the particular allergen. This process is known as sensitisation and means that the body is gearing up to fight the allergen the next time this is encountered.

Afterwards, each time the body encounters this allergen, there is an allergic reaction when this sensitisation occurs. This releases histamine into the body, which causes the symptoms of allergy. These symptoms appear in the form of asthma, hay fever or a red itchy skin rash called urticaria.

Histamine does a number of things that makes the allergic person uncomfortable. It dilates the blood vessels, causes swellings in the lining of the nose and airways, and causes leaking and mucus in the nose and respiratory passages. As the respiratory passages get into difficulty, it becomes hard to breathe properly and an asthma attack may occur.

Allergens are everywhere. The most common forms include pet fur, pollen, house dust mites, mould and certain medicines. Allergic people can also be irritated by common substances like pollution, smoke, perfume, and any strong smell.

Allergies occur in people in a number of different ways. These include asthma, hay fever and rhinitis, and eczema. Minor symptoms can be treated with over the counter products such as antihistamines, but asthma and eczema will require medical advice and prescription medicines to keep symptoms in check.

Testing for allergies
Your doctor will take a history of symptoms. Often a diagnosis can be made based on when, where and how symptoms arise. There are also a number of skin and blood tests that aid diagnosis. In the case of asthma, breathing tests will help to confirm a diagnosis.

Pet allergies
Allergens are found in the hair, saliva and urine of household pets. The pet doesn’t even have to live in your own home. Schools can be alive with allergens, brought in by pet owners. A pet allergy can be confirmed by an allergy test.

A person with a pet allergy will experience a range of reactions; asthma, eczema, rash, hayfever or eye symptoms such as itchiness or watering.

If you still want to have a pet there are measures that can improve matters. There are furless cats; you can wash your dog or cat regularly; you can consider a ‘cleaner’ pet such as a rabbit or guinea pig. Unfortunately, having a pet will always prove difficult because apart from the problem with fur, there may be allergens in urine, pet food etc. Even fish food can be problematic.

Avoiding allergens in the home
To avoid allergic symptoms, particularly pet allergies, a number of steps need to be taken in the home. The house should be pet free and as free from clutter as possible. Household furnishings and items should be well maintained and regularly cleaned and soft furnishings should be kept to a minimum in favour of wooden floors and wooden chairs etc. Things that can attract allergens such as soft toys, dried flowers etc. should also be avoided where possible. Regular vacuuming is essential and a vacuum cleaner that has no bag is preferable. Smoking should never be allowed in the house.

House dust mites
House dust mites are too tiny to see. They eat the flakes of skin that we constantly shed. They are present in furniture and carpets and especially in our beds. We breathe in their waste products and it is these that our breathing tubes are allergic to. As we spend a lot of time in bed, this is a favourite place for the house dust mite to live.

Signs of allergy to dust mites include wheezing when you are vacuuming or dusting; when you enter a dusty room or house; or asthma symptoms during the night or first thing in the morning.

There are several ways you can minimise house dust mites:
Direct sunlight kills the dust mite so put bedding in the sun every few weeks, preferably on the clothes line
When washing sheets or other bedding, use hot water if possible, as this also kills dust mites
Sheepskins used as undercovers are not recommended unless they can be frequently aired in the sun and washed
Beds need to be kept dry, especially cots and cribs
Ensure rooms are well vacuumed, damp-dusted and aired each week. Where possible keep dusty objects out of the bedroom
Carpets should be avoided if possible.
Covers can be purchased both for mattresses and pillows that act as a barrier to the house dust mite
Wash soft toys regularly in warm water or freeze them overnight

Pollens, moulds and fungal spores
Pollens can come from grasses, trees and shrubs. Privet has been highlighted as a trigger for asthma but not everyone with asthma is sensitive to it. Grasses and weeds are so widespread and have such a long season that they are the major pollen problem in Ireland. Most grasses and weeds have two or six month seasons.

You can minimise these by doing the following:
Replace any tree or shrub in your garden that makes your nose and eyes itch or makes you sneeze and wheeze. Wind pollinated plants should be avoided – they have light pollen that travels easily.
Take extra medicine during the months when you know pollens are likely to make your asthma worse. If you also get hay fever, medicines for this may be needed too.
Keep the house as warm and dry as possible to avoid moulds.
Remove mould or mildew from walls, shower curtains etc. with a fungicide e.g. very diluted household bleach.
Air clothes and wardrobes regularly.
Avoid contact with spores from rotting vegetation e.g. compost, leaf mould.
Mowing the lawn may disturb pollen and spores

Food and drink
The foods most commonly associated with food allergy are cow’s milk, wheat, seafood, eggs, soybeans and peanuts. These can cause your face, tongue and mouth to swell. Milk allergy affecting asthma occurs in probably one out of 50 children under the age of two. In older children and adults it is less frequent, about one in 500 people. Often it is not the food or drink as much as the substances or additives in them e.g. preservatives and colouring.

Common irritants in food include metabisulphite which is found in drinks; additive numbers 220, 223 and 224 which are found in foods like pickles, crisps and sausages; and the yellow colouring, tartrazine which is found in juices, sweets, syrups and sauces.

For more information, contact the Asthma Society of Ireland on freephone, 1850 44 54 64.

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