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Allergic reaction causes

An allergic reaction can be triggered by contact with any substance a person is allergic to, such as food, pollen or something else in the environment.

The body's immune system identifies these allergens as harmful and sends antibodies to fight them each time they are detected.

In allergic reactions, the antibody is called immunoglobulin E, or IgE.

These antibodies attach to special cells called mast cells, which release substances like histamine after coming into contact with the allergen.

This can cause allergy symptoms such as swelling, inflammation, itching, rashes, sneezing and a runny nose.

A common allergy treatment is antihistamine medicine which helps reduce allergy symptoms by blocking the effects of histamine.

Allergy triggers

Common allergy triggers include:

  • Pollen
  • Fungus and mould spores
  • Pet dander
  • House dust mites
  • Some foods
  • Insect stings or bites
  • Some medicines
  • Latex
  • Some household chemicals

Once a person identifies what may be causing their allergic reactions, they can take steps to try to reduce their exposure to these allergens.

Allergy risk factors

Allergic reactions may be more common if there is a history of allergies in the family.

Some medical conditions, such as asthma, can increase a person's risk of being affected by other allergies.

Environmental factors can also play a part, such as children being exposed to cigarettes smoke in the house, house dust mites, some pets and having had antibiotic treatment.

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WebMD Medical Reference

Medically Reviewed by Dr Rob Hicks on December 20, 2015

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