Allergy

An allergy is a chronic condition in which the immune system mounts an abnormal reaction to an ordinarily harmless substance called an allergen.

Notable studies

 * 1988, Allergy and the chronic fatigue syndrome
 * 2015, Increased Risk of Chronic Fatigue Syndrome Following Atopy: A Population-Based Study

Learn more

 * 1999, Allergies To Foods, Plants May Predict Chronic Fatigue Syndrome
 * 2019, Allergy Season Is Getting Longer and Nastier Each Year, Smithsonian Magazine