Allergies     

An allergy is a reaction in the body to a normally harmless substance. Usually the immune system functions as the body's defense against invading bacteria and viruses. In most allergic reactions, the immune system is responding to a false alarm. When you inhale an allergen (a substance that causes allergies), your immune system releases chemical substances that inflame the linings of your nose, sinuses, eyelids, lungs and eyes. This causes itching, sneezing, runny nose, watery eyes, coughing and, in people with hyper-reactive airways, wheezing.

Causes

Researchers think people may inherit the tendency to be allergic. Children are more likely to develop allergies if a parent has allergies, though they may not be allergic to the same substances. People who have allergies are frequently sensitive to more than one substance. Substances that cause the most allergic reactions include pollen, mold, dust mites and factors associated with pets (dander, proteins in saliva, dust from outdoors).

Pollen

Pollen allergy, also known as hay fever, occurs seasonally -- in the spring, summer and fall -- when trees, weeds and grasses release tiny particles, called pollen, which are carried through the air. In North America, most pollen comes from weeds, such as ragweed. Trees that produce allergenic pollen include oak, ash, elm, hickory, poplar, sycamore, maple, cypress, walnut and western cedar. Few people are allergic to flowers. In fact, most people have little contact with the pollen of flowering plants, which is carried by insects, not the wind.

Mold

Molds are another cause of seasonal allergies. The mold season often peaks from June to late summer, though people who are allergic may have symptoms from spring to late fall. In the warmest parts of the United States, molds can cause year-round allergies. Molds are part of the fungus family, and their spores (reproductive particles) can produce allergic reactions when inhaled. In homes, mold is common in damp basements, bathrooms, refrigerator drip trays, houseplants, air conditioners, humidifiers, garbage pails, mattresses and upholstered furniture. Molds can also be found in bakeries, breweries, barns, dairies, greenhouses, compost piles and outdoor areas that are moist and shady.

Dust Mites

Dust mites are microscopic organisms in the dust found in all homes and workplaces. These mites can live in bedding, upholstered furniture and carpets. They thrive in the summer and die in the winter, though in warm, humid homes, they can thrive year round. House dust, which is made up of a number of materials, contains dead dust mites and their waste products. It is these waste products that actually cause the allergic reaction.

Pets

Many people think that pet allergies are caused by the fur of cats and dogs. But researchers have found that the major allergens are proteins that come from the oil glands in the animals' skin and are shed in dander. Saliva, which sticks in the fur when an animal licks itself, and urine are also sources of allergy-causing proteins. Some rodents, such as guinea pigs, gerbils, mice and rats, can also cause allergic reactions in some people.

About Chemical Sensitivity

Some people report they have allergic reactions to things such as perfumes and tobacco smoke. Although the symptoms may resemble the symptoms of allergies, sensitivity to these substances is not the same as a true allergic reaction.

Symptoms

Signs and symptoms of allergies to airborne substances include:

• Sneezing, often with a runny or clogged nose

• Coughing and wheezing

• Itching eyes, nose and throat

• Dark circles under the eyes (caused by increased blood flow near the sinuses)

• Red, swollen or watering eyes

For people who have asthma, allergens can trigger asthma symptoms. Allergic reactions can also lead to sinusitis. You and your health care provider can diagnose allergies without a specific test based on your symptoms, when and how long you have them and what seems to trigger your symptoms. Your health care provider can use skin tests to determine what allergens are causing your symptoms. In these tests, diluted extracts from different allergens are injected under the skin. If you have an allergic reaction, a small, raised, reddened area appears on the skin where you had the injection.

Treatment

Treatment for allergies often involves using self-care steps to avoid the allergen. Some people may also need medications or allergy shots.

Medications

There are several different types of medications that can help with allergic reactions:

• Antihistamines can be used to counter the effects of histamine, which is the chemical released by the body that causes allergy symptoms. Antihistamines can cause drowsiness; however, some of the newer medications available by prescription do not. One of these newer medications is now available without prescription, loratidine. The advantage of the older antihistamines available without a prescription is that they take effect quickly. It can take a few days for the newer antihistamines to take full effect.

• Corticosteroid nasal sprays are effective against allergy symptoms. It can take three to 10 days to get maximum relief, so you should start them as soon as you begin having symptoms, or even before you start having symptoms if you can anticipate the season of your allergies.

• Decongestants can relieve symptoms caused by nasal allergies. They are available as oral medications and as nose drops and sprays, but drops and sprays should only be used for a few days. When used for longer periods, they can make symptoms worse.

• Eye drops containing antihistamines or decongestants can be prescribed to help relieve itchy eyes.

Allergy Shots

Allergy shots cause the immune system to react by producing varieties of antibodies and cells that do not cause dangerous symptoms, instead of producing antibodies and chemicals that result in allergy symptoms. On rare occasions, allergy shots also can be used to prevent certain medication allergies. Allergy shots are not used to treat food allergies, because the shots themselves are too likely to cause anaphylaxis. However, oral (swallowed) immunotherapy using extraordinarily diluted samples of allergy triggers is currently being tested as a possible new treatment for food allergy.

Self-Care

In addition to using medications, there are steps you can take to reduce your exposure to airborne allergens and the severity of your symptoms:

• Keep your windows and doors closed and use air conditioning at home and in your car during allergy season. Avoid using window and attic fans. Change your furnace/air conditioning filter frequently and use a filter that removes smaller particles.

• Stay indoors in the morning and on dry, hot, windy days, when outdoor pollen levels are highest.

• Be aware that pollen can be brought indoors on people and pets.

• Dry your clothes in a dryer rather than hanging them outside, where they can collect pollen.

• Avoid tobacco smoke, which can aggravate allergies.

• Run a dehumidifier at home to reduce humidity, which may allow mold to grow. Clean the dehumidifier often.

• Dustproof your bedroom: avoid wall-to-wall carpets, horizontal blinds, down-filled blankets and feather pillows. Bedding should be encased in a zippered, plastic, airtight and dustproof cover.

• Use a vacuum cleaner equipped with a high-efficiency particulate air (HEPA) filter.

• Washable items should be washed often using water hotter than 130 degrees F. Lower temperatures do not kill dust mites.

• If you must live with a pet you are allergic to, someone else should bathe the pet weekly and brush it often. Pets should be kept outside of the house if possible, or at least out of the bedroom.

• Avoid irritants that can make symptoms worse, such as insect sprays, tobacco smoke, air pollution and fresh tar or paint.