Allergy is an exaggerated immune response or reaction to substances that are generally not harmful. Allergy is caused by a highly sensitive immune system which leads to a misguided immune response. Normally, the immune system protects the body from harmful substances such as bacteria and viruses. An allergic reaction occurs when the immune system reacts to substances (allergens) that are usually harmless to which most people do not produce an immune response.

In a child with allergies, first exposure to an allergen stimulates the immune system to recognize the substance. Any subsequent exposure to allergens typically causes symptoms. When an allergen enters the body of a person who has the sensitized immune system, certain cells release histamine and other chemicals. This causes itching, swelling, mucus production, muscle spasms, hives, skin rash and other symptoms.

Allergies in Children — Symptoms

Symptoms vary in severity from one person to another. Most people have symptoms that not only cause the discomfort but also endanger their lives, while a few people have life-threatening reactions (called anaphylaxis).

The body part that comes into direct contact with the allergen influences the symptoms. For example, normally, inhaled allergens cause nasal congestion, itching in nose and throat, mucus production, coughing or wheezing. In general, food allergies can cause abdominal pain, cramping, diarrhea, nausea, vomiting or other severe life-threatening reactions. Often, any allergy to plants normally produces a rash and an allergic reaction to medications affects the whole body. Read more...