Allergies and Autoimmune Diseases Health Center

Allergies are any physical reaction to a substance outside the body -- a food, something in the environment, or a medication. Some, like hay fever, are a minor inconvenience; others, like some varieties of peanut allergy, can be life-threatening.

Autoimmune diseases are conditions in which the body's immune responses are triggered, causing it to attack itself. Certain people are genetically more likely to develop these diseases, and many of them are more prevalent in women.