An IgE-mediated immediate hypersensitivity reaction to the consumption of peanuts (the seeds of Arachis hypogaea). Peanut allergens are designated Ara by the World Health Organization. Peanut allergy is the single most important food allergy in the U.S., affecting more than a million people. Reactions to peanuts may range from mild (rashes) to life-threatening (closure of the airway, cardiac dysrhythmias, coma). About 50 people die of peanut allergy in the U.S. each year.