An allergy is a hypersensitivity disorder of the immune system. Allergic reactions occur when a person’s immune system reacts to normally harmless substances in the environment. A substance that causes a reaction is called an allergen. These reactions are acquired, predictable, and rapid. Allergy is one of the four forms of hypersensitivity and is formally called type I (or immediate) hypersensitivity. Allergic reactions are distinctive because of excessive activation of certain white blood cells called mast cells and basophils by a type of antibody called Immunoglobulin E (IgE). This reaction results in an inflammatory response which can range from uncomfortable to dangerous medical conditions.
According to the leading experts in allergy, an allergic reaction begins in the immune system. Our immune system protects us from invading organisms that can cause illness. If you have an allergy, your immune system mistakes an otherwise harmless substance as an invader. This substance is called an allergen. The immune system overreacts to the allergen by producing Immunoglobulin E (IgE) antibodies. These antibodies travel to cells that release histamine and other chemicals, causing an allergic reaction.
Mild allergies like hay fever are very common in the human population and cause symptoms such as red eyes, itchiness, running nose, eczema, hives, or an asthma attack. Allergies can play a major role in conditions such as asthma. In some people, severe allergies to environment, diet or medicines allergens may result in life-threatening reactions called anaphylaxis. Food allergies and reactions to the venom of stinging insects such as wasps and bees are often associated with severe reactions.
Allergies are among the most common chronic conditions worldwide. Symptoms of allergies range from making you miserable to putting you at risk for life-threatening reactions.
An allergic reaction typically triggers symptoms in the nose, lungs, throat, sinuses, ears, lining of the stomach or on the skin. For some people, allergies can also trigger symptoms of asthma. In the most serious cases, a life-threatening reaction called anaphylaxis may also occur.
A number of different allergens are responsible for allergic reactions. The most common include:
Allergic Rhinitis: It is also known as hay fever or pollinosis. If you sneeze a lot, if your nose is often runny or stuffy, or if your eyes, mouth or skin often feels itchy, you may have allergic rhinitis. Allergic rhinitis, like skin rashes and other allergies, develops when the body’s immune system becomes sensitized and overreacts to something in the environment that typically causes no problem otherwise in most people. Allergic rhinitis takes two different forms:
• Seasonal:Symptoms of seasonal allergic rhinitis can occur in spring, summer and early fall. They are usually caused by allergic sensitivity to airborne mold spores or to pollens from grass, trees and weeds.
• Perennial: People with perennial allergic rhinitis experience symptoms year-round. It is generally caused by dust mites, pet hair or dander, cockroaches or mold. Underlying or hidden food allergies rarely cause perennial nasal symptoms.
Some people may experience both types of rhinitis, with perennial symptoms getting worse during specific pollen seasons. There are also non-allergic causes for rhinitis.
If you or your child have allergy symptoms, an allergist / immunologist, often referred to as an allergist, can help you with a diagnosis. An allergist has advanced training and experience to properly diagnose the allergy and help you feel better and live better.