What Are Allergies?




Allergic diseases occur in people who are genetically predisposed and have had prior exposure to an environmental antigen. Antigens, or allergens, are usually protein molecules that are produced by plants or animals. Common allergens include pet dander, plant pollens, insect droppings and insect venom. Antigen exposure in genetically predisposed people, results in sensitization and eventually allergic symptoms. Allergic symptoms include nasal congestion, sneezing, runny nose, itchy watery eyes, chest tightness, wheezing and shortness of breath, skin rashes and gastrointestinal complaints. Food allergies are more common in children and can be severe. Symptoms of food allergy can be as mild as nausea, vomiting, diarrhea and skin rashes or as severe as asthma and anaphylactic shock.

Most allergies individuals have family members who also have allergies. If one parent has allergies, each child has a fifty percent chance of having allergies. If both parents have allergies, each child has a seventy five percent chance of having allergies. Children who develop skin problems (Eczema) at an early age are at a higher risk of developing allergic rhinitis and asthma as they grow up. Early diagnosis and treatment can prevent development of asthma in children. Allergy symptoms, and some of the medications used to treat allergies, can impair a child’s performance in school and an adult’s performance at work.

People who have developed sensitivities to environmental antigens (such as weed pollen, cat, dust mite, etc.) will have allergic reactions when they are exposed. Reactions start within minutes of exposure and will continue until you treat the symptoms and avoid the causative antigen. Allergic reactions have two phases, the first starting with the mast cells in your body releasing histamine. Histamine dilates the blood vessels. Dilating the blood vessels allows fluid to leak out of the blood into the tissue. Leakage of fluid into the tissues causes swelling and increased mucous production in mucous membranes.

The second phase is triggered by histamine and other mediators recruiting inflammatory cells (T cells and others) into the local area. Once enough inflammatory cells are present in the local area, these cells begin producing hormone like molecules called cytokines. Cytokines allow the inflammatory cells to communicate with each other and perpetuate the inflammatory response. It is this self-perpetuating inflammatory response which is responsible for the inability of antihistamines and decongestants to maintain long term control of allergic symptoms. Anti-inflammatory medications are necessary to turn off the second phase of the allergic response.

Common allergic diseases are allergic rhinitis, asthma, urticaria, anaphylaxis, allergic eczema, and food allergies.

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