A peanut allergy is a reaction that occurs when your body mistakenly identifies peanuts as harmful substances, causing your immune system to release chemicals, including histamine, into your blood. The allergy is fairly common; it's one of the most common causes of severe allergy attacks, and even tiny amounts of peanuts or products that contain them can cause a serious reaction.
A mild reaction may result in a runny nose, skin rash, stomachache or tingling on the lips or tongue, but reactions can worsen, causing throat tightening, wheezing, vomiting and diarrhea. People who are allergic to peanuts can also suffer from a life-threatening reaction called anaphylaxis, which can cause difficulty breathing, a dangerous drop in blood pressure and death. Anaphylaxis usually happens within minutes but can occur after several hours of consuming peanuts.