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Definition: Allergen

Allergen

An allergen is a substance that's capable of producing an allergic reaction. In some people with asthma, allergens that are breathed in can trigger symptoms such as coughing, wheezing, and shortness of breath. Allergens that commonly cause asthma symptoms include animal dander, dust mites, mold, and pollen.

get your flu shot by Halloween

The key is to get the vaccine at least two to three weeks before the flu season begins in order to have optimal protection against it. 

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