What are allergies?
Allergies are physiological reactions caused when the immune system reacts to a specific foreign substance (allergen) that has been inhaled, touched, or eaten by a person.
Normally, the human body defends itself against harmful substances, such as viruses or bacteria, but, sometimes, the defenses aggressively attack usually innocuous substances such as dust, mold, or pollen.
The immune system generates large amounts of the antibodies called immunoglobin E (IgE), to attack and destroy the supposed enemy. Each IgE antibody specifically targets a particular allergen—the substance that triggers the allergic reaction. In this disease-fighting process, inflammatory chemicals, such as histamines, cytokines, and leukotrienes are released or produced, and some unpleasant, and, in extreme cases, life-threatening, symptoms may be experienced by an allergy-prone person.
What are allergic reactions?
An allergic reaction may occur in the skin, eyes, lining of the stomach, nose, sinuses, throat, and lungs—places where immune system cells are located to fight off invaders that are inhaled, swallowed, or come in contact with the skin. Reactions may result in the following:
Seasonal or allergic rhinitis (nasal stuffiness, sneezing, nasal itching, nasal discharge, itching in ears or roof of mouth)
Allergic conjunctivitis (red, itchy, watery eyes)
Atopic dermatitis or eczema (red, itchy, dry skin)
Urticaria (hives or itchy welts)
Contact dermatitis (itchy rash)
Asthma (airway problems, such as shortness of breath, coughing, wheezing)
What causes allergic reactions?
Although hundreds of ordinary substances could trigger allergic reactions, the most common triggers, called allergens, include the following:
- Tree, grass, and weed pollens
- Natural rubber latex (protein)
- Dust mites
- Animal protein (dander, urine, oil from skin)
- Insect stings
- Cockroach droppings and body parts
Who is affected by allergy?
Allergies can affect anyone, regardless of age, gender, race, or socioeconomic status. Generally, allergies are more common in children. However, a first-time occurrence can happen at any age, or recur after many years of remission.
There's a tendency for allergies to occur in families, although the exact genetic factors that cause it aren't yet understood. Often, the symptoms of allergies develop gradually over a period of time.
Allergy sufferers may become so accustomed to chronic symptoms, such as sneezing, nasal congestion, or wheezing, that they do not consider their symptoms to be unusual. Yet, with the help of an allergist, these symptoms can usually be prevented or controlled and quality of life greatly improved.
How is allergy diagnosed?
In addition to a complete medical history and physical examination, your child's doctor may use the following:
- Skin test. The skin test is a method of measuring the child's level of IgE antibodies to specific allergens. Using diluted solutions of specific allergens, an allergist pricks the surface of the skin with these solutions on plastic prongs. A reaction to the skin test doesn't always mean that your child is allergic to the allergen that caused the reaction. Skin tests provide faster results, typically taking 15 minutes, and are more specific than blood tests.
- Blood test. The blood test is used to measure the child's level of IgE antibodies to specific allergens. One common blood test is called RAST (radioallergosorbent test).
- Challenge test. This is a test supervised by an allergist because a very small amount of allergen is taken by mouth or inhaled.
What is the treatment for allergy?
Specific treatment for allergy will be determined by your child's doctor based on the following:
- Your child's age, overall health, and medical history
- Extent of the disease
- Your child's tolerance for specific medications, procedures, or therapies
- Expectations for the course of the disease
- Your opinion or preference