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Allergy Overview

Allergies are diseases of the immune system that cause an overreaction to substances called "allergens." Allergies are grouped by the kind of trigger, time of year or where symptoms appear on the body: indoor and outdoor  allergies (also called "hay fever," "seasonal," "perennial" or "nasal" allergies), food allergies, latex allergies, insect  allergies, skin  allergies and eye  allergies. People who have allergies can live healthy and active lives.

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Glossary Glossary of Allergy Terms

 

What are Allergies

Allergies reflect an overreaction of the immune system to substances that usually cause no reaction in most individuals. These substances can trigger sneezing, wheezing, coughing and itching. Allergies are not only bothersome, but many have been linked to a variety of common and serious chronic respiratory illnesses (such as sinusitis and asthma). Factors such as your family history with allergies, the types and frequency of symptoms, seasonality, duration and even location of symptoms (indoors or outdoors, for example) are all are taken into consideration when a doctor diagnoses allergies. Additionally, allergic reactions can be severe and even fatal. However, with proper management and patient education, allergic diseases can be controlled, and people with allergies can lead normal and productive lives.

Common Allergic Diseases

  • Allergic rhinitis: (hay fever or “indoor/outdoor,” “seasonal,” “perennial” or “nasal” allergies): Characterized by nasal stuffiness, sneezing, nasal itching, clear nasal discharge, and itching of the roof of the mouth and/or ears. 

  • Allergic asthma: (asthma symptoms triggered by an allergic reaction): Characterized by airway obstruction that is at least partially reversible with medication and is always associated with allergy. Symptoms include coughing, wheezing, shortness of breath or rapid breathing, chest tightness, and occasional fatigue and slight chest pain. 

  • Food Allergy: Most prevalent in very young children and frequently outgrown, food allergies are characterized by a broad range of allergic reactions. Symptoms may include itching or swelling of lips or tongue; tightness of the throat with hoarseness; nausea and vomiting; diarrhea; occasionally chest tightness and wheezing; itching of the eyes; decreased blood pressure or loss of consciousness and anaphylaxis. 

  • Drug Allergy: Is characterized by a variety of allergic responses affecting any tissue or organ. Drug allergies can cause anaphylaxis; even those patients who do not have life-threatening symptoms initially may progress to a life-threatening reaction. 

  • Anaphylaxis: (extreme response to a food or drug allergy): Characterized by life-threatening symptoms. This is a medical emergency and the most severe form of allergic reaction. Symptoms include a sense of impending doom; generalized warmth or flush; tingling of palms, soles of feet or lips; light-headedness; bloating and chest tightness. These can progress into seizures, cardiac arrhythmia, shock and respiratory distress. Possible causes can be medications, vaccines, food, latex, and insect stings and bites. 
  • Latex Allergy: An allergic response to the proteins in natural, latex rubber characterized by a range of allergic reactions. Persons at risk include healthcare workers, patients having multiple surgeries and rubber-industry workers. Symptoms include hand dermatitis, eczema and urticaria; sneezing and other respiratory distress; and lower respiratory problems including coughing, wheezing and shortness of breath.  

  • Insect Sting/Bite Allergy: Characterized by a variety of allergic reactions; stings cannot always be avoided and can happen to anyone. Symptoms include pain, itching and swelling at the sting site or over a larger area and can cause anaphylaxis. Insects that sting include bees, hornets, wasps, yellow jackets, and fire and harvest ants.  

  • Urticaria: (hives, skin allergy): A reaction of the skin, or a skin condition commonly known as hives. Characterized by the development of itchy, raised white bumps on the skin surrounded by an area of red inflammation. Acute urticaria is often caused by an allergy to foods or medication. 

  • Atopic Dermatitis: (eczema, skin allergy): A chronic or recurrent inflammatory skin disease characterized by lesions, scaling and flaking; it is sometimes called eczema. In children, it may be aggravated by an allergy or irritant. 

  • Contact Dermatitis: (skin allergy): Characterized by skin inflammation; this is the most common occupational disease representing up to 40 percent of all occupational illnesses. Contact dermatitis is one of the most common skin diseases in adults. It results from the direct contact with an outside substance with the skin. There are currently about 3,000 known contact allergens. 

  • Allergic Conjunctivitis: (eye allergy): Characterized by inflammation of the eyes; it is the most common form of allergic eye disease. Symptoms can include itchy and watery eyes and lid distress. Allergic conjunctivitis is also commonly associated with the presence of other allergic diseases such as atopic dermatitis, allergic rhinitis and asthma.

 

SOURCE: This information should not substitute for seeking responsible, professional medical care. First created 1995; fully updated 1998; most recently updated 2005.
© Asthma and Allergy Foundation of America (AAFA)
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