Peanut allergy is one of the most common food allergies, particularly in the Western world. About 1 in 200 children may develop a peanut allergy by the time they reach five years of age.
Most cases of allergy become evident when a child reacts while consuming peanuts, with the allergy only being detected before a reaction occurs in 3% of cases, when a skin prick test is performed prior to peanut consumption.
Most children who are allergic to peanuts are also allergic to other nuts. The reactions are mediated by the chemical histamine and other substances released when the immune system identifies the presence of nut proteins.
Symptoms of peanut allergy may be mild or may manifest as a severe anaphylactic reaction. Symptoms of peanut allergy include:
- A red, blotchy and intensely itchy skin rash called urticaria, commonly referred to as hives
- Swelling (angioedema) of the face, eye lids, lips, tongue, roof of the mouth, or throat
- Abdominal cramps, diarrhea, nausea and vomiting
- Runny and itchy nose
- Runny eyes with itching and a gritty sensation, also called allergic conjunctivitis
- Exacerbation of existing eczema or atopic dermatitis
- Aggravation of existing asthma
- Allergic babies and infants may become pale, sleepy and may vomit
Anaphylaxis describes a severe and life threatening allergic reaction. An anaphylactic response is characterized by a swelling of the larynx (voice box) that disrupts the passage of air into the lungs, leading to severe shortness of breath. The swollen larynx also makes it difficult to speak and swallow. In addition, dilated blood vessels may cause a sharp fall of blood pressure, with the skin turning cool and clammy and the sufferer feeling dizzy or even losing consciousness. An intense feeling of dread and anxiety may be accompanied by a weak but rapid pulse.
Anaphylaxis requires immediate treatment with adrenaline. Young babies may simply collapse due to anaphylactic reaction in the absence of any apparent symptoms.