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What is an allergy?
An allergy is an over reaction of the body to a normally harmless substance. This harmless substance is also known as an allergen. Examples of allergens are pollen, cat dander, mold, fruits, and nuts. Allergy is also called hypersensitivity, which literally means overly sensitive.
During an allergic reaction, the immune system mistakenly believes that a harmless substance--an allergen--is harmful. The body tries to protect itself and creates an antibody to that allergen. This antibody serves as a trigger. The next time the person comes in contact with that allergen, the immune system releases massive amounts of histamines and other chemicals in order to protect the body. Unfortunately, these chemicals and histamines trigger a cascade of allergic symptoms that can affect the respiratory system, gastrointestinal tract, skin, or cardiovascular system.
There are many types of allergy. Some of the more common forms are:
- Food Allergy - A food allergy is an immune system response to a food that the body mistakenly believes is harmful. Examples of food allergy include wheat allergy, peanut allergy, milk allergy, and egg allergy.
- Pet Allergy - Examples of pet allergy include dog allergy and cat allergy, but any animal (birds, hamsters, rabbits, mice, gerbils, rats, and guinea pigs) can cause allergic reactions.
- Pollen and Fungi Allergy - A common example is allergy to ragweed pollen, which is called hayfever. Patients are typically allergic to grass and tree pollens, molds, and fungi.
- Household Allergy - This allergy includes allergens such as house-dust mite droppings, cat and dog dandruff, horse hair, and cockroach droppings.
- Drug Allergy - Allergy to antibiotics is a common form of drug allergy, though a patient can be allergic to almost any medication.
- Latex Allergy - Latex allergy is one of the most common occupational allergies and strikes health care workers. It produces varied symptoms, which commonly include runny nose, sneezing, itchy eyes, scratchy throat, hives, and other itchy, burning sensations.
Allergy can manifest itself in many ways. Some common allergy-related conditions are:
- Asthma -- Asthma is a chronic inflammatory condition of the lungs, which results in occasional airflow obstruction. This chronic inflammation causes spasms and swelling of the bronchial linings. There is a strong association between asthma and allergy. Exposure to allergens is one of the triggers of asthma.
- Rhinitis - Rhinitis includes hay fever and perennial rhinitis. Hay fever is the seasonal allergy that many people experience. It includes seasonal watery eyes, and runny nose. Perennial rhinitis or "permanent cold" is the allergic reaction to household allergens and can last year round.
- Dermatitis - Also called skin allergy, dermatitis includes rashes, dry flaking skin, or other skin manifestations that appear in relation to contact with an allergen. Hives are also an allergy-related condition and are known as urticaria.
- Anaphylaxis - This is a severe form of allergic reaction. Anaphylaxis is a sudden-onset, life-threatening reaction characterized by bronchial constriction and changes in blood flow (such as shock). Its clinical presentation may include respiratory, cardiovascular, cutaneous, or gastrointestinal manifestations. Any allergen can cause an anaphylactic reaction in any given person.
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Disclaimer: The information provided on this website is for educational purposes only and does not serve as a replacement for care provided by your own personal health care team. This website does not render or provide medical advice, and no individual should make any medical decisions or change their health behavior based on information provided here. All pertinent content provided on this website should be discussed with your personal physician to evaluate whether it has any relevance to or impact on your specific condition. Reliance on any information provided by this website is solely at your own risk.
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