Peanut allergy is a type of food allergy that affects millions of people worldwide. It is characterized by an immune system reaction to proteins found in peanuts, which can cause mild to severe symptoms ranging from hives, itching, and swelling to anaphylaxis, a life-threatening condition that requires immediate medical attention. People with peanut allergy must avoid all peanut-containing products and carry epinephrine auto-injectors in case of accidental exposure.