Center For Asthma And Allergy

What are Allergies

Allergies reflect an overreaction of the immune system to substances that usually cause no reaction in most individuals. These substances can trigger sneezing, wheezing, coughing and itching. Allergies are not only bothersome, but many have been linked to a variety of common and serious chronic respiratory illnesses (such as sinusitis and asthma). Additionally, allergic reactions can be severe and even fatal. However, with proper management and patient education, allergic diseases can be controlled, and people with allergies can lead normal and productive lives.

Common Allergic Diseases

Allergic rhinitis (hay fever or “indoor/outdoor,” “seasonal,” “perennial” or “nasal” allergies): Characterized by nasal stuffiness, sneezing, nasal itching, clear nasal discharge, and itching of the roof of the mouth and/or ears.
Allergic asthma (asthma symptoms triggered by an allergic reaction) : Characterized by airway obstruction that is at least partially reversible with medication and is always associated with allergy. Symptoms include coughing, wheezing, shortness of breath or rapid breathing, chest tightness, and occasional fatigue and slight chest pain.
Food Allergy: Most prevalent in very young children and frequently outgrown, food allergies are characterized by a broad range of allergic reactions. Symptoms may include itching or swelling of lips or tongue; tightness of the throat with hoarseness; nausea and vomiting; diarrhea; occasionally chest tightness and wheezing; itching of the eyes; decreased blood pressure or loss of consciousness and anaphylaxis.
Drug Allergy: Is characterized by a variety of allergic responses affecting any tissue or organ. Drug allergies can cause anaphylaxis; even those patients who do not have life-threatening symptoms initially may progress to a life-threatening reaction.
Anaphylaxis(extreme response to a food or drug allergy): Characterized by life-threatening symptoms. This is a medical emergency and the most severe form of allergic reaction. Symptoms include a sense of impending doom; generalized warmth or flush; tingling of palms, soles of feet or lips; light-headedness; bloating and chest tightness. These can progress into seizures, cardiac arrhythmia, shock and respiratory distress. Possible causes can be medications, vaccines, food, latex, and insect stings and bites.
Latex Allergy: An allergic response to the proteins in natural, latex rubber characterized by a range of allergic reactions. Persons at risk include healthcare workers, patients having multiple surgeries and rubber-industry workers. Symptoms include hand dermatitis, eczema and urticaria; sneezing and other respiratory distress; and lower respiratory problems including coughing, wheezing and shortness of breath.
Insect Sting/Bite Allergy : Characterized by a variety of allergic reactions; stings cannot always be avoided and can happen to anyone. Symptoms include pain, itching and swelling at the sting site or over a larger area and can cause anaphylaxis. Insects that sting include bees, hornets, wasps, yellow jackets, and fire and harvest ants.
Urticaria (hives, skin allergy) : A reaction of the skin, or a skin condition commonly known as hives. Characterized by the development of itchy, raised white bumps on the skin surrounded by an area of red inflammation. Acute urticaria is often caused by an allergy to foods or medication.
Atopic Dermatitis (eczema, skin allergy) : A chronic or recurrent inflammatory skin disease characterized by lesions, scaling and flaking; it is sometimes called eczema. In children, it may be aggravated by an allergy or irritant.
Contact Dermatitis (skin allergy) : Characterized by skin inflammation; this is the most common occupational disease representing up to 40 percent of all occupational illnesses. Contact dermatitis is one of the most common skin diseases in adults. It results from the direct contact with an outside substance with the skin. There are currently about 3,000 known contact allergens.
Allergic Conjunctivitis (eye allergy) : Characterized by inflammation of the eyes; it is the most common form of allergic eye disease. Symptoms can include itchy and watery eyes and lid distress. Allergic conjunctivitis is also commonly associated with the presence of other allergic diseases such as atopic dermatitis, allergic rhinitis and asthma.

SOURCE: This information should not substitute for seeking responsible, professional medical care. First created 1995; fully updated 1998; most recently updated 2005. © Asthma and Allergy Foundation of America (AAFA)

What are causes of Allergies

The substances that cause allergic disease in people are known as allergens. “Antigens,” or protein particles like pollen, food or dander enter our bodies through a variety of ways. If the antigen causes an allergic reaction, that particle is considered an “allergen” – and antigen that triggers an allergic reaction. These allergens can get into our body in several ways:

Inhaled into the nose and the lungs. Examples are airborne pollens of certain trees, grasses and weeds; house dust that include dust mite particles, mold spores, cat and dog dander and latex dust.
Ingested by mouth. Frequent culprits include shrimp, peanuts and other nuts.
Injected. Such as medications delivered by needle like penicillin or other injectable drugs, and venom from insect stings and bites.

What Makes Some Pollen Cause Allergies, and Not Others?

Plant pollens that are carried by the wind cause most allergies of the nose, eyes and lungs. These plants (including certain weeds, trees and grasses) are natural pollutants produced at various times of the year when their small, inconspicuous flowers discharge literally billions of pollen particles. Because the particles can be carried significant distances, it is important for you not only to understand local environmental conditions, but also conditions over the broader area of the state or region in which you live.

Unlike the wind-pollinated plants, conspicuous wild flowers or flowers used in most residential gardens are pollinated by bees, wasps, and other insects and therefore are not widely capable of producing allergic disease.

What is the Role of Heredity in Allergy?

Like baldness, height and eye color, the capacity to become allergic is an inherited characteristic. Yet, although you may be born with the genetic capability to become allergic, you are not automatically allergic to specific allergens. Several factors must be present for allergic sensitivity to be developed:

The specific genes acquired from parents.
The exposure to one or more allergens to which you have a genetically programmed response.
The degree and length of exposure.

A baby born with the tendency to become allergic to cow’s milk, for example, may show allergic symptoms several months after birth. A genetic capability to become allergic to cat dander may take three to four years of cat exposure before the person shows symptoms. These people may also become allergic to other environmental substances with age.

On the other hand, poison ivy allergy (contact dermatitis) is an example of an allergy in which hereditary background does not play a part. The person with poison ivy allergy first has to be exposed to the oil from the plant. This usually occurs during youth, when a rash does not always appear. However, the first exposure may sensitize or cause the person to become allergic and, when subsequent exposure takes place, a contact dermatitis rash appears and can be quite severe. Many plants are capable of producing this type of rash. Substances other than plants, such as dyes, metals, and chemicals in deodorants and cosmetics, can also cause a similar dermatitis.

Diagnosis

If you break out in hives when a bee stings you, or you sneeze every time you pet a cat, you know what some of your allergens are. But if the pattern is not so obvious, try keeping a record of when, where, and under what circumstances your reactions occur. This can be as easy as jotting down notes on a calendar. If the pattern still isn’t clear, make an appointment with your doctor for help.

Doctors Diagnose Allergies in Three Steps:

Personal and medical history. Your doctor will ask you questions to get a complete understanding of your symptoms and their possible causes. Bring your notes to help jog your memory. Be ready to answer questions about your family history, the kinds of medicines you take, and your lifestyle at home, school, and work.
Physical examination. If your doctor suspects an allergy, he/she will pay special attention to your ears, eyes, nose, throat, chest, and skin during the physical examination. This exam may include a pulmonary function test to detect how well you exhale air from your lungs. You may also need an X-ray of your lungs or sinuses.
Tests to determine your allergens. Your doctor may do a skin test, patch test or blood test.
Skin test. For most people, skin tests are the most accurate and least expensive way to confirm suspected allergens. There are two types of allergen skin tests. In prick/scratch testing, a small drop of the possible allergen is placed on the skin, followed by lightly pricking or scratching with a needle through the drop. In intra-dermal (under the skin) testing, a very small amount of allergen is injected into the outer layer of skin.
With either test, if you are allergic to the substance, you will develop redness, swelling, and itching at the test site within 20 minutes. You may also see a “wheal” or raised, round area that looks like a hive. Usually, the larger the wheal, the more sensitive you are to the allergen.
Patch test. This test determines if you have contact dermatitis. Your doctor will place a small amount of a possible allergen on your skin, cover it with a bandage, and check your reaction after 48 hours. If you are allergic to the substance, you should develop a rash.
Blood testsAllergen blood tests (also called RAST, ELISA, FAST, MAST, RIST, STALLERSYM, or CAP tests) are sometimes used when people have a skin condition or are taking medicines which interfere with skin testing. Your doctor will take a blood sample and send it to a laboratory. The lab adds the allergen to your blood sample, and then measures the amount of antibodies your blood produces to attack the allergens.

Treatment

Good allergy treatment is based on the results of your allergy tests, your medical history, and the severity of your symptoms. It can include three different treatment strategies: avoidance of allergens, medication options and/or immunotherapy (allergy shots).

Avoiding Your Allergens : The best way to prevent allergy symptoms and minimize your need for allergy medicine is to avoid your allergens as much as possible and to eliminate the source of allergens from your home and other environments. For important tips, talk to your doctor.

Medication : Some people don’t take allergy medicines because they don’t take their symptoms seriously (“Oh, it’s only my allergies.”) The result may be painful complications such as sinus or ear infections. Don’t take the risk. There are so many safe prescription and non-prescription medicines to relieve allergy symptoms! Following is a brief list of medications taken for allergies. They are available in non-prescription and prescription form:

Antihistamines and decongestantsare the most common medicines used for allergies. Antihistamines help relieve rashes and hives, as well as sneezing, itching, and runny nose. Prescription antihistamines are similar to their non-prescription counterparts, but many of them do not cause drowsiness. Decongestant pills, sprays, and nose dropsreduce stuffiness by shrinking swollen membranes in the nose.

It is important to remember that using a non-prescription nasal decongestant spray more than three days in a row may cause the swelling and stuffiness in your nose to become worse, even after you stop using the medicine. This is called a “rebound” reaction. Some non-prescription “cold” medicines combine an antihistamine, a pain reliever like aspirin or acetaminophen, and a decongestant. Aspirin can cause asthma attacks in some people. Don’t take a chance: if you have asthma, talk with your doctor before taking any non-prescription allergy medicine.

Eye drops may provide temporary relief from burning or bloodshot eyes. However, only prescription allergy eye drops contain antihistamines that can reduce itching, tearing and swelling.
Corticosteroid creams or ointmentsrelieve itchiness and halt the spread of rashes. Corticosteroids are notthe same as anabolic steroids that are used illegally by some athletes to build muscles. If your rash does not go away after using a non-prescription corticosteroid for (a week?), see your doctor.
Corticosteroid nasal sprays help reduce the inflammation that causes nasal congestion without the chance of the “rebound” effect found in non-prescription nose sprays.
Cromolyn Sodiumprevents the inflammation which causes nasal congestion. Because it has few, if any, side effects, cromolyn can be safely used over long periods of time.
Oral Corticosteroids may be prescribed to reduce swelling and stop severe allergic reactions. Because these medications can cause serious side effects, you should expect your doctor to carefully monitor you.
Epinephrinecomes in pre-measured, self-injectable containers, and is the only medication which can help during a life-threatening anaphylactic attack. To be effective, epinephrine must be given within minutes of the first sign of serious allergic reaction.

*New prescription and non-prescription drugs are approved periodically. If the prescription you are taking is not on this list, ask your doctor which category (above) it falls into, so that you can refer to this chart.

Immunotherapy (Allergy Shots) : When it is not possible to avoid your allergens and treatment with medications alone does not solve the problem, immunotherapy can often prevent allergy symptoms. It involves giving a person increasingly higher doses of their allergen over time. The person gradually becomes less sensitive to that allergen. This can be effective for some people with hay fever, certain animal allergies, and insect stings. It is usually not effective for allergies to food, drugs, or feathers, nor is it effective for hives or eczema.

Prevention

There are some simple things you can do to prevent allergies at home, work school, outside and when you travel.

At Home.

Dust to control mites. By dusting surfaces and washing bedding often, you can control the amount of dust mites in your home.
Vacuum often. Although cleaning can sometimes trigger allergic reactions, with dust in the air, vacuuming once or twice a week will reduce the surface dust mites. Wear a mask when doing housework and consider leaving for a few hours after you clean to avoid allergens in the air. You can also make sure your vacuum has an air filter to capture dust.
Reduce pet dander. If you have allergies, you should avoid pets with feathers or fur like birds, dogs and cats. Animal saliva and dead skin, or pet dander , can cause allergic reactions. If you can’t bear to part with your pet, you should at least keep it out of the bedroom.
Shut out pollen. When you clean your windows, do you see a film of pollen on the frame or sill? One easy way to prevent pollen from entering your home is to keep windows and doors closed. Use an air filter and clean it regularly or run the air conditioner and change the filter often.
Avoid mold spores. Mold spores grow in moist areas. If you reduce the moisture in the bathroom and kitchen, you will reduce the mold. Fix any leaks inside and outside of your home and clean moldy surfaces. Plants can carry pollen and mold too, so limit the number of houseplants. Dehumidifiers will also help reduce mold.

At Work.

Allergies at home and work are similar and affect millions of people each year. Allergy symptoms, like sneezing, nasal congestion and headache, may make it difficult to concentrate. Every work environment will have specific allergy problems so talk to your health care provider or pharmacist about how you can prevent allergies at your specific workplace.

At School.

Children may face allergens in the classroom and playground. In fact, children in the United States miss about two million school days each year because of allergy symptoms. Parents, teachers and health care providers can work together to help prevent and treat childhood allergies. Monitor the classroom for plants, pets or other items that may carry allergens. Encourage your child to wash his/her hands after playing outside. Many of the allergens in thehome will also be found at school. Although it may not be an option to vacuum or dust the classroom, there may be treatment options to help a child manage his/her symptoms during the school day.

Outside.

There are certain times during the year when plants and trees release pollen into the air. The timing of these pollen seasons depends on your geographic location. Different regions have different types of plants that pollinate at different times. Depending on where you live, allergy seasons may be mild or severe. Experts estimate that 35 million Americans suffer from allergies because of airborne pollen!

Tiny particles that are released from trees, weeds and grasses are known as pollen. These particles are carried by the wind from tall treetops all the way to your nose. But before you shrug off fancy flowers in fear of sniffles, remember that the types of pollen that most commonly cause your allergies are from plain-looking plants, such as trees, grasses and weeds. These plants produce small and light pollen, perfect for catching a ride on a gentle breeze.

Similar to pollen, mold spores are a seasonal pest. If you are sensitive to mold spores, you may have symptoms from spring to late fall. Yet, even after the first frost of winter, some mold spores can continue to grow in freezing temperatures. The severity of your mold spore allergies can depend on the climate that you live in. In the warmest areas of the United States, mold spores grow all year! But before you move to Antarctica, remember that mold spores also grow indoors, making it a year-round problem.

Traveling.

We are all on the go and there are a few things to keep in mind to prevent outdoor allergies during peak season, when the pollen count is high.

Stay inside during peak pollen times, usually between 10:00 a.m. and 4:00 p.m.
Keep your car windows closed when traveling
Stay indoors when humidity is high and on days with high wind, when dust and pollen are more likely to be in the air
Wear a facemask if you are outside to limit the amount of pollen you inhale
Shower after spending time outside to wash away pollen that collects on your skin and hair

Planes, Trains and Automobiles.

If you suffer from allergies, there may be other concerns when you travel. The allergy climate may be different than the one where you live. When you travel by car, bus or train, you may find dust mites, mold spores and pollen bothersome. Turn on the air conditioner or heater before getting in your car and travel with the windows closed to avoid allergens from outside. Travel early in the morning or late in the evening when the air quality is better.

When flying to your favorite vacation spot, remember that air quality and dryness on planes can affect you if you have allergies. If a cruise is your next vacation, be aware of the season and temperature at your destination(s). In tropical, damp climates there are allergens like dust mites, mold spores and pollen. In cold, damp climates, you may be exposed to dust mites and mold spores. Once you arrive at your hotel, there may be dust mites and mold spores lurking. If you are staying with family or friends, the same types of allergens that you find at home may be present.