What are Allergies?

Allergy Cartoon video (Osaka Japanese cartoon):

AAAAI What is an Allergic Reaction video

AAAAI Rhinitis Video


Allergy refers to the exaggerated reaction of the immune system in susceptible people, when it is exposed to a protein called an allergen. An allergen can take the form of tree pollen, peanut, cat dander, stinging insect venom, penicillin, and latex, among many others. Exposure to the allergen causes immune cells to release substances such as histamine in parts of the body which lead to itching, swelling, sneezing, hives, wheezing, low blood pressure, and sometimes, even death.

Allergens do not cause symptoms in all people, only in a group of people who develop Immunoglobulin E (IgE) to the particular allergen. IgE is the molecule responsible for triggering the allergic response in most people and its detection in the blood or the skin is an important part of the process when we determine whether or not someone has allergies.

An allergic reaction results in the release of the chemical histamine into the blood and different parts of the body. Histamine causes increased production of mucus, itching, swelling, muscle spasms, and leakage and dilation of blood vessels. Where the histamine is released determines the symptoms of the allergic reaction as follows:

Eyes: watery eyes, itching, red eyes

Nose: Sneezing, itchy nose, runny nose, congestion

Lungs: Cough, wheezing, difficulty breathing (due to airway muscle spasms)

Gastro-Intestinal: Nausea, vomiting, diarrhea, abdominal spasms

Skin: Itching, hives, swelling

Circulatory System: Dizziness, Low blood pressure, palpitations, passing out

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