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What is allergic asthma?

Allergic asthma is the most common type of asthma.

Asthma symptoms begin when the body reacts to something a person is allergic to, such as pollen, pet fur, feathers, mites or mould.

Allergic asthma tends to run in families where there's a history of asthma or other allergies, such as hayfever.

Because allergens are everywhere, it is important that people with allergic asthma understand their allergy and asthma triggers so they can help avoid them and know what to do when symptoms begin.

What is an allergy?

A major task of your immune system is to protect you from bacteria and viruses. However, in people with allergies, the IgE portion of the immune system is too vigilant. It may treat harmless substances, like pollen or cat fur, as if they were enemy invaders and attack them in your nose, lungs, eyes and under your skin.

When your body encounters an allergen, it creates special cells called IgE antibodies. These defensive cells trigger the body's allergic reaction. They cause the release of chemicals like histamine, which result in swelling and inflammation. This creates familiar allergy symptoms like a runny nose, itchy eyes and sneezing because your body is trying to destroy the allergens.

What is allergic asthma?

If you have allergic asthma, your airways are hypersensitive to the allergens to which you have become sensitive. Once these allergens get into your airways, your immune system overreacts. The muscles around your airways tighten (an effect called bronchospasm). The airways themselves become inflamed and flooded with thick mucus.

Whether you have allergic asthma or non-allergic asthma, the symptoms of asthma are generally the same and may include any or all of the following:

Common allergens for allergic asthma

Allergens, which are small enough to be inhaled deep into the lungs, include:

You may also have allergic reactions if you are scratched with an allergen (causing itchy, red skin), get some in your eyes (causing itchy, red eyes), or eat it, which in rare cases can cause life-threatening anaphylactic shock (including a severe asthma attack).

Remember that allergens are not the only things that can worsen your allergic asthma. Irritants may still trigger an asthma attack, even though they do not cause an allergic reaction. These irritants include:

  • Tobacco smoke
  • Smoke from a fireplace, candles, incense or fireworks
  • Air pollution
  • Cold air, especially vigorous exercise in cold air
  • Strong chemical odours or fumes
  • Perfumes, air fresheners or other scented products
  • Dusty workplaces

Your doctor can arrange allergy and asthma tests to determine exactly which indoor and outdoor allergens cause your allergic asthma. The two most common and recommended tests are:

  • Skin-prick test - pricking the skin with a tiny amount of the allergen and measuring the size of the red bumps 20 minutes later
  • A blood test: specific IgE test - used to be called RAST test

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