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Tests and Services

Evaluation for Allergy

What are allergies?
Allergies are physiological reactions caused when the immune system reacts to a specific foreign substance (allergen).

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 histamine, 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:
  • rhinitis - nasal stuffiness, sneezing, nasal itching, nasal discharge, itching in ears or roof of mouth.
  • allergic conjunctivitis - red, itchy, watery eyes.
  • atopic dermatitis - 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:
  • pollens
  • molds
  • dust mites
  • animal protein (dander, urine, oil from skin)
  • foods
  • medicines
  • feathers
  • insect stings
  • cockroaches

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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 is a tendency for allergies to occur in families, although the exact genetic factors that cause it are not 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, the Children’s team may use the following:
  • skin test
    The skin test is a method of measuring the child's lskin response to IgE antibodies to specific allergens. Using diluted solutions of specific allergens, the physician applies them to a small prick or puncture. Reaction appears as a small red area on the skin. A reaction to the skin test does not always mean that your child is allergic to the allergen that caused the reaction. Skin tests provide faster results 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).
Treatment of allergies:
Specific treatment for allergies will be determined by your child's physician based on the following:
  • your child's age, overall health, and medical history
  • severity of the allergic reaction
  • your child's tolerance for specific medications, procedures, or therapies
  • expectations for the course of the allergic reaction
  • your opinion or preference
The three most effective ways to treat allergies are avoidance, immunotherapy, and medication.

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What is avoidance?
Avoidance is staying away from a substance that causes an allergic reaction.

Suggestions for avoiding (some) allergens:
  • Remain indoors when the pollen count is high and on windy days.
  • Dust-proof the home, particularly your child's bedroom.
    • Eliminate, when possible, wall-to-wall carpet.
    • Wash bedding weekly in hot water to eliminate dust mites.
    • Keep mattresses, box springs, and pillows in dust covers.
    • Use air conditioning instead of opening the windows.
    • Consider putting a dehumidifier in damp areas of the home, but remember to clean it often.
    • Have your child wear a face mask if playing outside when the pollen count is high.
    • Take vacations in areas where pollen is not as prevalent - such as near the ocean. Your child's physician will also have suggestions for avoiding the allergens that cause reactions.

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    What is immunotherapy (allergy shots)?
    Immunotherapy is a type of treatment for allergic children with hay fever and/or asthma. It is also called desensitization, hyposensitization, and allergy shots. A mixture of the various pollens, mold spores, animal danders, and dust mites to which the child is allergic is formulated. This mixture is called an allergy vaccine. This vaccine contains no medication such as antihistamines or corticosteroids.

    How is immunotherapy administered?
    Immunotherapy is given by injection under the skin usually into the fatty tissue in the back of the arm. It is not painful like an injection into the muscle, such as a penicillin shot.

    How often are immunotherapy injections necessary?
    Injections may be given weekly or twice a week until a maximum dose is tolerated. This is called the maintenance dose. It may take 6-7 months to reach the maintenance dose. At this point, the frequency of injections may be decreased to every other week and finally to once a month. Your child's physician will establish the appropriate schedule of injections to meet your child's medical needs.

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    Symptom improvement and immunotherapy:
    About 80 to 90 percent of children improve with immunotherapy. It usually takes from 12 to 18 months before definite reduction in allergy symptoms is noticed. In some children, a reduction in symptoms is evident in as soon as six to eight months.

    Immunotherapy is only part of the treatment plan for allergic children. Since it takes time for immunotherapy to become effective, your child will need to continue the allergy medications, as prescribed by his/her physician. It is also important to continue eliminating allergens (such as dust mites) from your child's environment.

    Are there side effects to immunotherapy?
    There are two types of reactions to immunotherapy: local and systemic. The local reaction is redness and swelling at the injection site. If this condition occurs repeatedly, then the vaccine strength or schedule is changed.

    A systemic reaction is one that involves a different site, not the injection site. The symptoms may include nasal congestion, sneezing, hives, swelling, wheezing, and low blood pressure. Such reactions can indeed be serious and life threatening. However, deaths related to immunotherapy are extremely rare. If a systemic reaction occurs, your child may continue taking shots, but of a lower dosage.

    If you have any questions concerning immunotherapy, always consult your child's physician or allergist.

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    Medication as treatment for allergy:
    For children who suffer from allergies, there are many effective medications. This is a brief overview of the most commonly used types of medications. Always consult your child's physician before giving your child any over-the-counter medications.

    What are antihistamines?
    Antihistamines are used to relieve or prevent the symptoms of allergic rhinitis (hay fever) and other allergies. They prevent the effects of histamine, a substance produced by the body during an allergic reaction. Antihistamines come in tablet, capsule, liquid, or injection form and are available both over-the-counter and by prescription.

    What are decongestants?
    Decongestants are used to treat nasal congestion and other symptoms associated with colds and allergies. Decongestants cause the blood vessels to narrow, thus, leading to the clearing of nasal congestion. Decongestants are available both over-the-counter and by prescription. The most commonly used forms are liquid and tablet. However, nose sprays or drops may be prescribed by your child's physician for use for a few days.

    What are types of medications used for asthma and respiratory symptoms resulting from an allergic reaction?
    The use of medications for asthma or respiratory symptoms from allergies is highly individualized based on the severity of the symptoms. The following are the most commonly used medications:
    • bronchodilators
      These medications are used to help open the narrowed lungs and may relieve coughing, wheezing, shortness of breath, or difficulty in breathing. These are usually considered rescue medications for acute attacks of asthma. Types of bronchodilators are beta-agonists, theophylline, and anticholinergics. These medications come inhaled, in pill form, liquid, or injectables. The short-acting bronchodilators are used as needed, as symptoms occur. Longer-acting bronchodilators may be used for maintenance or on a daily basis to help control flare-ups from occurring.
    • anti-inflammatory medications
      These medications help to decrease the inflammation that occurs in the airways with asthma. These include two types of medications:
      • nonsteroidal anti-inflammatory medications
        Cromolyn and nedocromil are two types of nonsteroidal medications that are usually inhaled.
      • corticosteroids
        These medications can be given in a variety of ways. Some of them are inhaled, while others may be taken as a pill or liquid, or even injected. The steroids taken by mouth can have more side effects than those that are inhaled. Consult your child's physician regarding the best choice for your child.
    • Leukotriene antagonists
      These are used to help control the symptoms of asthma. These medications help to decrease the narrowing of the lung and to decrease the chance of fluid in the lungs or the nose. These are usually given by mouth.
    Consult your child's physician for more information concerning allergy medications.

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    Evaluation for Allergy - Departments & Programs - Children's National Medical Center