Treatement - Allergies
What are allergies?
Allergies are the immune system’s inappropriate and exaggerated response to a foreign substance. Exposure to what is normally a harmless substance, such as pollen, causes the immune system to react as if the substance is harmful. Substances that cause allergies are called allergens.
When you come into contact with an allergen, you may experience a number of symptoms including itchy, watery nose and eyes; asthma symptoms such as wheezing and coughing; or hives.
What is an allergic reaction?
An "allergic reaction" is the result of how three factors interact in the body:
- The allergen — Allergens include pollen, mold, animal dander, dust mites, medications, foods, latex, and others.
- Mast cells — Although mast cells are found throughout the body, most reside in connective tissues such as those of the skin, tongue, the lining of the nose and intestinal tract, the lungs, and upper airways. Similar cells, called "basophils" are present in the circulation.
- Immunoglobulin E (IgE) — IgE is an allergic antibody, a type of protein made by the immune system to recognize and fight specific body "invaders." IgE coats the surface of the mast cells in tissues and basophils in the bloodstream.
The first time an allergy-prone person is exposed to an allergen (such as pollen), large amounts of the corresponding IgE antibodies (for example, pollen IgE antibodies) are produced. The IgE antibodies cause the mast cells to release inflammatory chemicals that cause swelling of tissues, as well as histamine and several other chemicals that cause itching, engorgement of blood vessels, increased secretions, and bronchospasm (tightening of muscles that surround the airways). Some of these chemicals attract white blood cells known as eosinophils. The eosinophils add more inflammatory chemicals.
If the allergen is in the air, the allergen is inspired (breathed in), and an allergic reaction will occur in the eyes, nose, and/or lungs. If the allergen is ingested, an allergic reaction will occur in the mouth, stomach, and intestines. Sometimes enough inflammatory chemicals are released to cause a reaction throughout the body, such as hives, decreased blood pressure, shock, or loss of consciousness. This severe type of reaction is called anaphylaxis and may be life-threatening.
What is allergic rhinitis?
Nasal allergy symptoms and hay fever are referred to as "allergic rhinitis." Seasonal allergic rhinitis describes nasal allergies that change with the seasons due to pollen from plants (trees, grasses, or weeds). Seasonal symptoms arise during the pollinating seasons for particular plants. Because you can be allergic to more than one thing, your symptoms may get worse at different times throughout the year, or they may appear constant (perennial).
Does everyone get allergies?
No. Most allergies are inherited, which means they are passed on to children by their parents. People inherit a tendency to be allergic, although not to any specific allergen. If a child develops an allergy, it is very likely that at least one of his or her parents has allergies.
How common are allergies?
An estimated 50 million Americans, or 1 in 6 people, now have allergic rhinitis. Allergic disorders are the sixth leading cause of chronic illness in the United States, according to the Allergy Report from the American Academy of Allergy, Asthma and Immunology.
How are allergies diagnosed?
If you think you have allergies, don’t wait to see if your symptoms will go away. When your symptoms last longer than a week or two and tend to recur, make an appointment with an allergy/immunology specialist so a complete evaluation can be performed.
Allergy skin testing may be used to identify the allergens that are causing your allergy symptoms. The test is performed by pricking your skin with an extract of an allergen, and then evaluating the skin’s reaction.
If a skin test cannot be performed, a radioallergosorbent blood test (RAST) may be taken, although its results are not as sensitive as a skin test. This RAST evaluates the number of antibodies produced by the immune system. Elevated levels of certain antibodies can identify particular allergies.
How are allergies treated?
The most important aspect of treatment is avoidance, but these measures will usually be incomplete. Medications such as antihistamines, decongestants, or a combination of both are available over-the-counter or by prescription to treat allergy symptoms. Nasal sprays such as topical nasal steroids and cromolyn sodium also can be used to treat allergy symptoms. Asthma medications to reduce symptoms due to allergy include inhaled steroids, inhaled and oral bronchodilators, oral anti-leukotrienes, and injected medications including omalizumab – a monoclonal anti-IgE antibody. Immunotherapy, or "allergy shot therapy", is recommended for symptoms not adequately controlled with a combination of avoidance measures and regular medication use, and has been shown to be effective in properly selected patients with allergic rhinitis and/or allergic asthma.
Can allergies be cured?
Allergies cannot be cured, but symptoms can be controlled using a combination of avoidance measures and medications, and allergen immunotherapy in properly selected cases.