An allergic reaction to peanuts can cause wheezing, coughing, swelling, vomiting, trouble breathing and tightness in the throat, KidsHealth states. The person may have diarrhea or an upset stomach and develop hives and itchy, watery eyes. A severe reaction can progress to anaphylaxis, which further limits the ability to breathe and may cause an individual to lose consciousness.
When a person has a peanut allergy, the immune system treats peanut proteins like an infection and tries to fight them off, according to KidsHealth. Allergy symptoms occur because the body reacts by releasing histamine and other chemicals, and a second wave can be triggered hours after the initial exposure. People with deadly allergies may need to carry an epinephrine auto-rejector at all times to administer medication in an emergency.
Although many foods contain warnings about peanut allergies, a person may be exposed accidentally when food products are made in areas where nuts are also prepared. Peanut products are present in many forms in baked goods, candy, sauces and marinades, chili, ice cream, pudding, vegetarian products, pancakes and even specialty pizzas, according to Food Allergy Research & Education. Peanut products are commonly used in international cuisine, such as Asian, Mexican and African restaurants, and these foods are considered high risk. As of 2014, food manufacturers are only required to include the word "peanut" on their labels if it's an actual ingredient in the product.