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Hay Fever

Allergy Epidemic?

Medical Author: Alan Szeftel, MD, FCCP
Medical Editor: William C. Shiel Jr., MD, FACP, FACR

Find out what may be causing an increase in allergic diseases.Allergic rhinitis (hay fever), asthma and atopic eczema are among the most common causes of chronic ill health. There is also clear evidence that in the Western world these disorders are increasing in frequency. In Sweden, for example, the number of children with allergic rhinitis, asthma or eczema has doubled over a 12-year period.

The development of allergic disease relates to a complex interplay of genetic and environmental differences. Since no significant genetic changes have occurred in the last two decades, we must assume that environmental factors are most likely responsible for this trend. The reunification of Germany offered tremendous insight into the impact of environmental changes on allergic conditions. These disorders were less common in East Germany than in West Germany before reunification, where as since that geopolitical change occurred, the prevalence of allergic problems (except asthma) has increased among children who spent their early childhood in East Germany.

Hay Fever Overview

Most likely you or someone you know has allergies. The telltale itchy, puffy, watery eyes and red, stuffy nose signal changes in the seasons in homes and workplaces across the country. What these people suffer from is allergic rhinitis, or hay fever. The medical name for this condition refers to stuffy and itchy nose ("rhin-"), the most common symptom.

Hay fever is an allergic reaction. It is your immune system's response to foreign material in the air you breathe. Hay fever usually refers to allergies to outdoor, airborne materials such as pollens and molds.

About 15-20% of the population of the United States has some degree of hay fever. It is found equally in both men and women. Usually hay fever is seasonal, but it can last all year long if the allergen stays throughout the year. Spring and fall are the main hay fever seasons.



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Hay Fever

What are allergies?

An allergic reaction occurs when the immune system responds to a foreign substance in an abnormal fashion. The immune system normally protects the body from harmful agents like bacteria and toxins. The body's abnormal response to a harmless substance (called an allergen) is called a hypersensitivity, or an allergic reaction. Generally, these reactions are due to interactions between the allergen and the family of proteins, IgE, resulting in activation of cells in the body called mast cells and basophils.

What causes allergies?

Many substances in the environment can become allergens, but only in genetically susceptible persons. Dust mites, animal hair or danders, pollens, medications, foods, and insect venoms are examples of allergens. Approximately 20% of the US population is potentially allergic.

Reactions may be in the nose (hay fever), eyes (conjunctivitis), chest (asthma), or it can be systemic (anaphylaxis), me...

Read the Allergy and Hay Fever Medications article »


Read What Your Physician is Reading on eMedicine

Allergic Rhinitis »

Rhinitis is defined as inflammation of the nasal membranes1 and is characterized by a symptom complex that consists of any combination of the following: sneezing, nasal congestion, nasal itching, and rhinorrhea.

Read More on eMedicine »

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