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Exercise Induced Anaphylaxis

written by: Dr Mike C • edited by: Lamar Stonecypher • updated: 4/23/2010

Asthma and allergies affect many people in the western world. In extreme cases, allergies and asthmatic attacks may lead to anaphylactic shock which needs urgent medical attention and can be fatal. In some cases, anaphylaxis will occur during, or shortly after, the victim has exercised.

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    Asthma, allergies and anaphylaxis

    For the vast majority of people, allergies and asthma are simply annoying conditions that have to be lived with. They can be triggered by a wide range of sources (allergens) including things like, pollens (tree, grasses and flower), house dust mites; moulds; certain foods and various sources of air pollution, to name just a few.

    Allergies represent an over-reaction of the body to an agent which most of us would see as harmless. Allergies can express themselves in a variety of ways ranging from redness and sore patches on the skin to itchy eyes and runny noses, but they can also affect organs within the body. One of the major cellular mediators produced in an allergic response is histamine (this is why anti-histamine drugs are often used to treat allergies).

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    Histamine

    The role of histamine release in the body is as follows:

    • Causes dilation of blood vessels – this may be seen as redness in the affected area.
    • Makes the blood vessels more permeable – causing swelling in affected tissues and may make breathing difficult if the respiratory system is involved
    • Stimulates nerves cells causing symptoms such as itching, sneezing, soreness of the eyes, coughing
    • Stimulates the production of mucus (nose; airways; digestive tract) – may result in runny nose; crying; coughing; phlegm production.
    • Causes muscles in the airways and gut to contract – this causes wheezing symptoms and breathing difficulties to appear in the airways and abdominal cramps in the gut.

    Although at first site, these responses seem extreme, they are part of the body’s natural defense mechanism – the problem is that in allergy, it is responding inappropriately to (usually) benign stimuli.

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    Anaphylaxis

    Anaphylaxis is usually caused by the ingestion of a foodstuff that the sufferer is allergic to (other people will be able to consume the same food with absolutely no ill effects). The consumption of the problem foodstuff (allergen) causes the body to release large amounts of histamine which causes a number of reactions within the body. It can be caused by an allergic response to a sting or bee venom and can be the result of a severe asthmatic attack also. Anaphylaxis is a potentially fatal condition and if an episode is suspected, the victim needs urgent medical attention.

    Anaphylactic episodes can be brought on by exercise in people who suffer from allergies or a respiratory disease such as asthma or rhinitis, but the trigger is most likely to be the disease or an allergic reaction to a foodstuff consumed before exercise rather than the sport itself. When you exercise, you inhale more deeply and frequently. This would mean that an allergic patient could be more susceptible to airborne allergens when exercising and that they would penetrate further into the airways than they would otherwise do. In the event that somebody experiences an anaphylactic shock, urgent medical assistance is imperative. If you know that you are at risk, you should discuss the possibility of carrying an emergency kit (epinephrine) with your doctor – it could save your life!