What are Allergic Reactions

Allergic reactions are more common occurrences than you might otherwise believe because allergic reactions can encompass anything from a sty in the eye to life-threatening anaphylactic shock.


An allergic reaction is the body’s way of responding to a perceived “invader” or foreign substances called antigens.


These protein antigens will trigger the immune system.

In the case of individuals who suffer from allergic reactions this response is often a hypersensitivity reaction.

This means that the reaction is above and beyond what is necessary in order to protect the body from a particular antigen.

Almost anything can be an allergen, such as dust, pollen, medication, insect venom, animal dander, viruses and bacteria.


Reactions will also vary between a small skin rash and itchy eyes to an all over body rash. The reaction can also include one or several symptoms.


Allergies are very common and account for more than 17 million visits to the doctor on an annual basis.


More than half of these visits are for seasonal allergies.


An allergic reaction may not happen the first time you’re exposed. For example, you might be stung by a bee in the first time only have pain and redness. The second time you may have hives or difficulty breathing because the immune system now responds in a hyperactive way to that protein or allergen.


Allergies also occur with other diseases such as asthma, ear infections, sleep apnea and sinusitis.


When the allergen enters the body a reaction occurs in the immune system.


The immune system activates a protective antibody called immunoglobulin E to fight invading substances.

Even though everyone has IgE in their body, those who have allergy problems have an unusually large amount. This army of antibodies attacks the allergic substance and in variably injures mast cells. When these cells are injured or irritated they release histamine which results in an allergic reaction.



MedlinePlus: Allergic Reactions

American Academy of Allergy, Asthma and Immunology: Allergic REactions: Tips to Remember

KidsHealth.org: Serious Allergic Reactions

University of Maryland Medical Center: Allergic Reactions

National Institute of Allergy and Infectious Disease: Food Allergy

Northwestern University: Kids with Food Allergies Can Fall Through the Cracks

Congressionally Directed Medical Research Programs: Genetic Studies of Food Allergies