Allergic Reaction Causes
Many substances can trigger an allergic reaction.
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The body's immune system has a patrol of white blood cells, which produce antibodies.
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When the body is exposed to an antigen -- a substance that causes the immune system to make antibodies against it -- a complex set of reactions begins.
- The white blood cells produce an antibody specific to that antigen. This is called "sensitization."
- The job of the antibodies is to detect and destroy substances that cause disease and sickness. In allergic reactions, the antibody is called immunoglobulin E, or IgE.
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This antibody promotes production and release of chemicals and hormones called "mediators."
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Histamine is one well-known mediator.
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Mediators have effects on local tissue and organs in addition to activating more white blood cell defenders. It is these effects that cause the symptoms of the reaction.
- If the release of the mediators is sudden or extensive, the allergic reaction may also be sudden and severe.
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- Your allergic reactions are unique to you. For example, your body may have learned to be allergic to poison ivy from repeated exposure.
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Most people are aware of their particular
allergy
triggers and reactions.
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Certain foods, medications, latex, aspirin , shellfish, dust, pollen, mold, animal dander, and poison ivy are famous allergens.
- Bee stings, fire ant stings, penicillin , and peanuts are known for causing dramatic reactions in some people that can be serious and involve the whole body.
- Minor injuries, hot or cold temperatures, exercise , or even emotions may be triggers.
- Often, the specific allergen cannot be identified unless you have had a similar reaction in the past.
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- Allergies and the tendency to have allergic reactions run in some families. You may have allergies even if they do not run in your family.
- Many people who have one trigger tend to have other triggers as well.
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People with certain medical conditions are more likely to have allergic reactions.
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Severe allergic reaction in the past
- Asthma
- Lung conditions that affect breathing, such as chronic obstructive pulmonary disease (COPD)
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Nasal polyps
- Sensitive skin
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WebMD Medical Reference

