| − | Allergy is a condition in which the body has an exaggerated response to a substance (e.g. food or drug). Allergy is also known as hypersensitivity. | + | Allergy is a condition in which the body has an exaggerated response to a substance (e.g. food or drug). Allergy is also known as hypersensitivity.<ref>http://www.cdc.gov/vaccines/about/terms/glossary.htm#a</ref> |