evidence: Peanut allergy is a condition that causes the body's germ-fighting immune system to react to peanuts. It's one of the most common causes of a life-threatening allergic reaction to food. This life-threatening reaction is known as anaphylaxis. [...] Peanut allergy is the most common cause of anaphylaxis due to food. This medical emergency requires treatment with an epinephrine autoinjector (EpiPen, Auvi-Q, others) and a trip to the emergency room. Epinephrine is a kind of adrenaline. [...] Peanut allergy occurs when the immune system flags peanut proteins as harmful. When exposed to peanuts, the immune system releases symptom-causing chemicals into the bloodstream. These chemicals cause an allergic reaction.