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What Causes Allergy?When a plant or animal substance which is foreign to the human, invades the body (through the membranes of the eyes, nose or throat) an immune reaction occurs which is intended to counteract such invasion. Under ordinary circumstances that is a helpful, natural protection. However, some individuals exhibit an exaggerated inflammatory response to certain substances. This response is termed an allergic response. It is a trait that tends to run in families.
The allergens stimulate the body to form sensitizing antibodies which then combine with the allergens. The combination causes the body to release a number of chemicals that produce undesirable effects. Histamine is the best known of these chemicals; it causes swelling of the nasal membranes, itching, irritation and excess mucus production.
What Pollens Cause Trouble?Early springtime allergy is most often caused by pollens or common trees such as elm, maple, birch, poplar, beech, ash, oak, walnut, sycamore, cypress, hickory, mountain cedar, pecan, cottonwood and alder. Late springtime pollens come from the grasses, i.e. timothy, orchard, red top, sweet vernal, Bermuda , Johnson and some bluegrasses. Colorful or fragrant flowering plants rarely cause allergy, because their pollens are too heavy to be airborne. They rely on insects (bees and butterflies) to carry their pollens from one plant to another.
The most significant allergy producing pollen in the United States comes from ragweed. It begins pollinating in late August and continues through October or until the first frost. Other allergenic weeds of lesser importance also pollinate in this season.
What about MOLDS?Molds are fungi that spoil bread, rot fruit, and mildew clothing. They also grow on dead leaves, grass, hay, straw, grains, and on other plants and in the soil. Since they are not killed by frost, the mold allergy season is long. Mold spores may be in the outside air year-round except when snow covers the ground.
Indoors, molds grow on houseplants and in their soil. They also grow in damp places such as basements and laundry rooms. Molds can also be found in cheeses and fermented alcoholic beverages.
What Causes Year-Round Allergies?Allergens that are present through all seasons include animal dander (cats, dogs, horses and other pets, wool and feathers), cosmetics, molds, foods and house dust. House dust is a complex mixture of disintegrating cellulose (furniture stuffing), molds, dandlers (i.e. from household animals) and insect parts and small mites. Allergies that become worse in wintertime, when the hot air furnaces are turned on, are usually due to house dust.
What does an initial allergy evaluation involve?The initial visit includes a complete medical history and a focused physical examination. In some instances the upper airway is assessed with examination scopes. In some cases pulmonary function tests may be performed. In most instances tests for specific allergies are performed.
How are allergy tests performed?Testing for specific causes is usually done by skin testing. Drops of extracts of the substances known to cause allergic reactions are placed on the arm and a plastic device is pressed into the drops to allow them to soak into the skin. Reactions occur at the site within 20 minutes if the person is allergic to the material. When results on the arm are not conclusive, a few tests may be performed on the forearm. Solutions of allergens are injected into the skin and the sites are observed for 20 minutes for the appearance of allergic reactions.
How are allergic diseases treated?There are three approaches to dealing with allergic disorders:
- Avoidance of the causes
- Medications to suppress the reactions
- Allergy vaccines that decrease the person’s reactions to the allergens
In order to intelligently apply these measures we must establish that the problem is an allergy, and then identify the causes.
What are the advantages and disadvantages of taking allergy shots?The likelihood that allergic rhinitis or asthma will spontaneously go away is approximately 1% per year. That means medications usually will be needed for many years. The main advantage of allergy vaccines is that they greatly diminish the severity of a person’s allergic reactions, reducing the need for medications while further reducing symptoms. The disadvantages of allergy vaccine are that several injections are needed to build up to the monthly maintenance injections, and the person might have an allergic reaction to an injection. Many people would rather have monthly injections for 3 years than take medications for an indefinite period of time.