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Allergic Reaction (cont.)

Allergic Reaction Causes

Almost anything can trigger an allergic reaction.

  • The body's immune system involves the white blood cells, which produce antibodies.
    • When the body is exposed to an antigen, 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 help white blood cells detect and destroy substances that cause disease and sickness. In allergic reactions, the antibody is belong to the class of immunoglobulins known as immunoglobulin E or IgE.
  • This antibody type promotes production and release of chemicals and hormones called "mediators."
    • 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.
    • Histamine is one of the better-known mediators produced by the body.
    • If the release of the mediators is sudden or extensive, the allergic reaction may also be sudden and severe, and anaphylaxis may occur.
  • Allergic reactions are unique for each person. Reaction time to allergens can vary widely. Some people will have an allergic reaction immediately; for others, it will take time to develop.
  • Most people are aware of their particular allergy triggers and reactions.
    • There are more than 160 allergenic foods. Certain foods are common allergens, including peanuts, strawberries, shellfish, shrimp, dairy, and wheat.
    • Babies can also have food allergies. Common foods that can cause allergic reactions in babies include milk, eggs, nuts, and soy. People should talk to their child's pediatrician if they are concerned about food allergies in their baby.
    • Food intolerance is not the same as food allergies. Allergies are an immune system response, while food intolerance is a digestive system response in which a person is unable to properly digest or break down a particular food.
  • Vaccines and medications (antibiotics such as penicillin, amoxicillin, aspirin, ibuprofen, iodine), general anesthesia and local anesthetics, latex rubber (such as in gloves or condoms), dust, pollen, mold, animal dander, and poison ivy are well-known allergens. Other known allergens can include detergents, hair dyes, cosmetics, and the ink in tattoos.
  • Bee stings, fire ant stings, penicillin, and peanuts are known for causing dramatic reactions that can be serious and involve the whole body.
  • Minor injuries, hot or cold temperatures, exercise, stress, or emotions may trigger allergic reactions.
  • Sun exposure may cause allergic reactions in some people, often referred to as "sun poisoning."
  • Often, the specific allergen cannot be identified unless someone has had a similar reaction in the past.
  • Allergies and the tendency to have allergic reactions run in some families.
  • Many people who have one trigger tend to have other triggers as well.
  • Risk factors for allergic reactions include certain medical conditions that can make a person more likely to have allergic reactions:
Medically Reviewed by a Doctor on 3/16/2015

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