Hay Fever Symptoms Worse in Spring Than Summer: Study
Later exposure may spur less reaction or sufferers might just get used to symptoms, researchers say
URL of this page: http://www.nlm.nih.gov/medlineplus/news/fullstory_120072.html
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Friday, December 23, 2011
In the study, researchers compared daily pollen counts during the 2007 and 2008 hay fever seasons with daily symptoms reported by hay fever sufferers living around Leiden in the Netherlands.
The study participants were also tested for other common allergies, including birch pollen, house dust mites, dogs and cats.
The investigators found that hay fever symptoms matched the concentration of pollen in the air and also the amount of medication taken by the participants. They took more medication on days with high pollen counts and severe hay fever symptoms and less medication on days with low pollen counts and milder hay fever symptoms.
But hay fever symptoms were reportedly worse during the spring than summer for a similar pollen count, according to the study published online Dec. 21 in the journal Clinical and Translational Allergy. This finding could not be explained by medication use or other allergies.
"It is possible that sufferers report their symptoms as milder later in the season because they get used to their hay fever, or that the pollen from late-flowering species is less allergenic than pollen from early-flowering grass," study leader Dr. Letty de Weger, of Leiden University Medical Center, said in a journal news release.
"However, there has been other work which suggests that high exposure to grass pollen early in the season may down-regulate inflammation on subsequent contact possibly via the production of allergen-specific regulatory T cells," de Weger added.
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