Allergies are traditionally associated with spring and summer, when high pollen counts fill the air and leave hay fever sufferers sneezing and scratching at sore eyes. But winter brings its own allergens, with dust mites and mold spores spelling misery for a whole new batch of sufferers.Allergic reactions occur when the immune system responds to the presence of a foreign substance. When it suspects an invasion, the immune system produces proteins called antibodies.

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