hay fever

hay fever, seasonal allergy causing inflammation of the mucous membranes of the nose and eyes. It is characterized by itching about the eyes and nose, sneezing, a profuse watery nasal discharge, and tearing of the eyes. The cause is a sensitivity to one or more species of pollens or fungi. In addition, many patients with hay fever develop other allergic conditions, e.g., asthma and sinusitis. In the spring, hay fever may be caused by tree pollens (oak, elm, maple); in summer, by grass pollens, wheat or corn rusts, or fungus spores; in late summer and fall, by ragweed pollen, which is the most common cause. Temporary relief of symptoms may be obtained from antihistamines and decongestants, such as ephedrine. Physicians may resort to corticosteroids in severe cases. Sometimes desensitization measures are taken, consisting of repeated injections of small amounts of the allergen (pollen) until its presence produces no symptoms; however, the treatment must be continued from year to year, since immunity is not permanent. Some relief can be obtained by removing pollen from the air by air conditioners and filters.

Seasonal sneezing, nasal congestion, and tearing and itching of the eyes caused by allergy to the pollen of certain plants. These plants are chiefly those pollinated by the wind (e.g., ragweed in North America, timothy grass in Britain). Antihistamines and corticosteroids may provide temporary relief, but the most effective long-range treatment is desensitization. Unless properly treated, about one-third of patients with hay fever develop asthma.

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See Hay fever