What Are Allergies

What are allergies?

Allergies result when the body's immune system overreacts to a substance that is normally harmless. The substance, which is referred to as an allergen, could be anything from the pollen of a specific tree to a particular ingredient in a medication. It could be a puppy's dander or a food such as peanuts. While not everyone experiences allergies, some people are allergic to one specific thing, while others suffer a wide variety of different reactions to different allergens. Two of the most common types of allergies are seasonal outdoor allergies (seasonal allergic rhinitis) and year-round indoor allergies (perennial allergic rhinitis). Those who sneeze and sniffle at certain times of the year can blame pollen for their symptoms. Tree pollen flourishes in the spring, while grass and weed pollen takes over in late summer and early autumn. Indoor allergens like dust, mould, mildew, and animal dander can irritate eyes, noses, and throats all year round.

Why do people get allergies? To someone with allergies, the tiniest thing can cause the biggest trouble. A seemingly harmless bit of dust, dander from a cat, or a puff of pollen floating in the air can lead to allergy symptoms. Ever wonder why the human body reacts the way it does? Why do we sneeze? Why do our noses run and our eyes tear up? Basically, an allergy is the body's over-eager reaction to a misinterpreted threat. When exposed to an allergen, the body responds by trying to block it out - or sneeze it out. It's good to know that your immune system works so hard to protect you, but for those with seasonal or year-round allergies, this defence usually leads to inflammation. It's the inflammatory response that causes that congested feeling and the need to sneeze. Your eyes may go on the defensive, too; tears may form and blood vessels may swell and give you that puffy, red-eyed look.

Who is at risk for allergies? Genetic tendencies play a role since allergies tend to run in families. You might not be allergic to the exact same things as them, but if one or both of your parents have had seasonal or year-round allergies, you're likely to as well. That said, allergies can develop at any age, though a person will usually develop allergies during childhood or early adulthood. Environmental exposure may also play a role in triggering allergies. For example, some people who are consistently exposed to allergens (e.g., people whose work exposes them to seed dust) may be more at risk of developing allergies. Research has also shown that infants exposed to cigarette smoke may be at increased risk for allergies.

What are the symptoms of allergies? When the immune system reacts to allergens, it attempts to mount a strong defence. Because much of its defence relies on blocking out or getting rid of offending allergens, most allergy symptoms have something to do with inflammation. Congested nasal passages can turn into a runny nose and swollen, red eyes can become itchy and watery. The sinus pressure of congestion combined with the exhaustion from sneezing, coughing, blowing your nose, or gasping for air can lead to sleeplessness and some difficulty concentrating on everyday tasks. If you suffer from seasonal allergies, you may notice that your allergy symptoms are worse in the morning. This is because pollen counts are the highest in the morning.

Avoiding indoor allergens For some people, allergy season lasts all year and its symptoms strike close to home. It can be challenging to avoid your allergy triggers when they're all over your house, but it can be done. Deal with dust. Keep the house as dust-free as possible. When dusting, use a damp cloth. The dust will cling to the cloth better this way, keeping it from floating off into the air. Regularly wash bedding linens in hot water, and choose sturdy but lightweight fabric blankets that can withstand weekly washings.

The vacuum may seem like an ally to those with allergies, but older vacuums can actually stir up dust. If you can, either wear a protective face mask or find a newer model vacuum with a high efficiency particulate air filter, better known as a HEPA filter. If all else fails, ask someone else to vacuum for you. Smooth the surfaces. Dust clings to random clutter like clothes, books, and paperwork. Piles of pillows may please the eye, but they're dust collectors, too, as are stuffed toys. Houseplants seem like they would be good for the air, but they tend to accumulate dust and mould. You can regularly wipe down surfaces to get rid of dust, but you can also simply reduce the number of dustgathering surfaces in your home. Opt for hardwoods or linoleum over carpet and rugs, and choose window shades instead of heavy fabric curtains or dust-catching blinds. Minimize the mould. A cool, well-ventilated home with low humidity levels will invite less mould. Closed-in spaces such as closets, basements, and especially bathrooms are mould magnets. Shower curtains tend to get mouldy after repeated use and should either be regularly bleached or simply replaced. Protect yourself from pet dander. Unfortunately, most experts would recommend removing allergycausing animals from the house. You may also want to consider implementing a strict "No pets allowed" policy in bedrooms. Another option is to adopt a hypoallergenic pet that is less likely to cause allergic reactions.

Avoiding outdoor allergens Pollen plays such a pivotal role in the cycles of the natural world. Pollen causes the telltale seasonal shifts in plants, grasses, and weeds. Pollen also causes the telltale seasonal allergy symptoms so many people suffer from at various times throughout the year. How can a person prone to seasonal allergies coexist with nature without sneezing, sniffling, and coughing? Know your triggers. Pollen is the number one culprit in most outdoor seasonal allergies, but pollen from where? Tree pollen causes most springtime symptoms, and the pollen from grasses and weeds set off summer and fall sneezing fits. Leave pollen where it belongs. Pollen is not as sticky as some allergens but it can come into your house in the air; on your clothes, skin, and hair; and on the fur of pets. Keep the windows closed during allergy seasons, and regularly clear out air filters and air ducts. After being outside in "danger" zones, remove any shoes and clothing that may have gotten soiled with pollen. Take a shower, or at least wash your hands and rinse out your eyes and nose. Sidestep your triggers. Nature doesn't have to be your enemy! Try to minimize your exposure to your known allergy triggers and if you have seasonal allergies, make the best of the times of the year when you're not suffering from allergy symptoms. For example, if you're allergic to spring tree pollen, save campouts and picnics for late summer or early autumn. If autumn ragweed stuffs you up, make spring your hiking season. Watch the weather. Pollen is the substance that plants such as trees, weeds, and grasses use to fertilize new seeds for growth. A pollen count is the number of grains of plant pollen per cubic meter, usually measured over a 24-hour period. Most weather forecasts feature pollen counts that can give you a rough estimate of daily allergy hazards, so pay attention to these and limit your time outdoors on days when the pollen counts soar. Pollen counts are also highest in the morning, so try to stay indoors until later in the day.

Allergy treatment basics Sometimes, avoiding allergens is just not possible or not enough to prevent the troublesome symptoms of allergic rhinitis. When this happens, allergy treatment using medications may be necessary. There are a wide range of treatments available for allergy sufferers, including prescription and nonprescription products. These include: nasal medications eye drops oral medications allergy shots If you are able to predict when your allergies start (e.g., seasonal allergic rhinitis), you should start preventative measures (including medication) beforehand so that your symptoms are minimized. Your doctor or pharmacist can help you find a treatment that's right for you.

When choosing a treatment, you should consider the following factors: Is this treatment option tolerable (i.e., what are the side effects)? How often do I need to use the medication? How long do I have to use the medication? Will it interact with my other medication(s)? How quickly will I get relief? Will the treatment resolve all my allergy symptoms? What can you expect from your allergy therapy? Goals for allergy prevention and treatment include: 1.

prevention of allergy symptoms (e.g., by avoiding your allergy triggers)

2.

relief and control over the symptoms caused by your allergies

3.

minimal or no side effects from the medications

Oral medications Oral medications (i.e., taken by mouth) for allergic rhinitis include antihistamines and decongestants. Oral medications for allergies available in Canada include: non-prescription 1.

antihistamines

1.

loratadine (Claritin® and others)

2.

cetirizine (Reactine® and others)

3.

diphenhydramine (Benadryl® and others)

4.

chlorpheniramine (Chlor-Tripolon® and others)

5.

fexofenadine (Allegra® and others)

6.

desloratadine (Aerius®)

2.

antihistamine and decongestant combination products

1.

fexofenadine - pseudoephedrine (Allegra-D®)

2.

cetirizine - pseudoephedrine (Reactine® Allergy & Sinus)

3.

triprolidine - pseudoephedrine (Actifed®)

4.

loratadine - pseudoephedrine (Claritin® Allergy & Sinus)

3.

decongestants

1.

phenylephrine (Sudafed PE® and others)

2.

pseudoephedrine (Eltor®, Sudafed® and others) prescription

1.

1.

antihistamines azatadine (Optimine®)

2.

leukotriene receptor antagonists

1.

montelukast (Singulair®)

Antihistamines work by stopping the action of histamine, which is a substance in your body that causes an allergic response when you are exposed to an allergen. Antihistamines reduce the symptoms of eye itching, nasal itching, runny nose, sneezing, and watery eyes, while oral decongestants help with nasal congestion. Desloratadine is an antihistamine that also relieves nasal congestion. Antihistamines and oral decongestants can be used together to relieve allergy symptoms.

The third type of oral allergy medications is leukotriene receptor antagonists (montelukast), which work by blocking leukotrienes. Leukotrienes are chemicals that are released by your body during an allergic response. They are also involved in causing allergy symptoms. Side effects of oral medications

1.

The side effects of antihistamines may include dry mouth, constipation, drowsiness, difficulty urinating, and decreased reaction time. At normal recommended doses, cetirizine, desloratadine, fexofenadine, and loratadine have fewer side effects than other antihistamines. 2. The side effects of decongestants include headache, dizziness, dry mouth, palpitations (rapid, irregular heartbeat), tremor, and trouble sleeping. Normal doses of oral decongestants can also increase the blood pressure in people who have high blood pressure. People who have severe or poorly controlled high blood pressure should not take oral decongestants.

3.

The most common side effects of montelukast include diarrhea, stomach pain, headache, thirst, itchy skin, and rash. Some oral medications may affect people with certain medical conditions (including high blood pressure, glaucoma, and low thyroid) and may not be a suitable treatment option. To ensure that you are taking the most appropriate medication, inform your doctor and pharmacist of any other medications you are taking and any medical conditions you have. You should follow your doctor's and pharmacist's instructions on taking the medication to ensure you get the most benefit from it. If you are taking any of these medications and your allergy symptoms do not go away completely, talk to your doctor. Nasal medications Nasal medications (nose sprays) for allergies are available in a few different classes. Nasal medications for allergies available in Canada include: non-prescription decongestants

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phenylephrine (Little Noses Decongestant Nasal Drops®, and others) oxymetazoline (Dristan®, and others) xylometazoline (Balminil Nasal Decongestant®, Otrivin®, and others)

mast cell stabilizers

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sodium cromoglycate (Cromolyn® and others)

prescription anticholinergics

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ipratropium (Atrovent Nasal Spray®)

antihistamines

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levocabastine (Livostin Nasal Spray®)

corticosteroids

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ciclesonide (Omnaris®) fluticasone furoate (Avamys®) fluticasone proprionate (Flonase® and others) beclomethasone (Gen-Beclo AQ® and others) triamcinolone acetonide (Nasacort AQ®) budesonide (Rhinocort Aqua® and others) mometasone (Nasonex®) flunisolide (Rhinalar® and others)

Nasal decongestants provide temporary relief from congestion. However, they should not be used for more than 3 to 7 days because nasal congestion can return or get worse once you stop the medication. Since allergic rhinitis usually requires long-term treatment, it's best to talk to your doctor or pharmacist about which medication is right for you. Mast cell stabilizers help with nasal itchiness, sneezing, and runny nose. They work by stopping the action of mast cells, which are thought to be involved in your body's allergic reaction response. They work best when used as a preventative measure, before allergy symptoms start. Otherwise, it may take up to 4 weeks to feel relief. Dosing may be up to 4 times a day. Side effects may include local irritation, sneezing, stinging, bad taste in the mouth, and nosebleeds. Antihistamines help relieve nasal itchiness, sneezing, and runny nose. They work by stopping the action of histamine, which is a substance in your body that causes an allergic response when you are exposed to an allergen. It is used 2 to 4 times a day. Side effects may include nasal irritation, drowsiness, nosebleeds, dry mouth, and headaches. Anticholinergics are used to relieve a runny nose associated with allergies. They work by blocking the secretion of mucous in the nose. It is used 2 or 3 times a day. Side effects may include headaches, nosebleeds, nasal irritation, dry nose, and sore throat. Corticosteroids are nasal sprays that treat symptoms locally (at the site of irritation) to help relieve the symptoms of allergic rhinitis, including itching, congestion, runny nose, and sneezing. They work by locally reducing inflammation in the nose that is involved in an allergic reaction and provide relief of your allergy symptoms. The dosing of corticosteroids is once or twice a day, depending on the medication selected. Side effects of corticosteroids may include burning, stinging, nasal irritation, headaches, nosebleeds, sore throat, changes in taste, and dry mouth. Corticosteroids are not the same as anabolic steroids, the substances people hear of in reference to athletes and performance-enhancing drugs. The corticosteroids in nasal sprays are safe when used as recommended by your doctor. For more information, see the FAQ section on allergy medications. Each person may respond differently to medications and some treatments are gentler than others. If side effects are a concern for you, talk to your doctor about which nasal spray would best suit you. To use the nasal spray:

1.

First, gently blow your nose.

2.

Wash your hands well with soap and water.

3.

You may need to prime the nasal spray pump first but spraying it a few times into the air until a fine mist appears.

4.

Keep your head upright or tilted slightly forward.

5.

Use the "opposite hand to opposite nostril" technique. With your right hand, spray the medication into the left nostril toward the outside of the nose. Remember to breathe in deeply through your nose as you pump the spray.

6.

Repeat for the other nostril.

7.

Put the cap back on the nasal spray container.

8.

For more detailed instructions, see the package insert for your particular medication or check with your doctor or pharmacist.

People with certain medical conditions should not take some of these nasal medications. To ensure you are taking the most appropriate medication, inform your doctor and pharmacist of any other medications you are taking and of any medical conditions you have. You should follow your doctor's and pharmacist's instructions on using the medication to ensure you get the most benefit from it. If you are taking any of these medications and your allergy symptoms do not go away completely, talk to your doctor. Eye drops Eye drops used to treat allergies are specifically for eye symptoms such as red, itchy, and watery eyes. Eye drops for allergies available in Canada include: non-prescription antihistamine and decongestant combination products

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phenylephrine - pheniramine (AK Vernacon®)

decongestants

 

naphazoline (Clear Eyes®, Naphcon Forte®, and others) oxymetazoline (Claritin Eye Allergy Relief®, Visine Workplace®, and others)

mast cell stabilizers



sodium cromoglycate (Cromolyn®, Opticrom®, and others)

prescription antihistamines

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levocabastine (Livostin®) olopatadine (Patanol®) ketotifen (Zaditor®) emedastine (Emadine®)

mast cell stabilizers

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lodoxamide (Alomide®) nedocromil (Alocril®)

Antihistamine eye drops provide relief of eye symptoms (i.e., ocular symptoms) in a few minutes. Decongestant eye drops also work in about 5 to 10 minutes. The mast cell stabilizers take a few days to see their full effects. Dosing for these medications is usually 2 to 4 times a day, depending on the type of eye drops used. Side effects may include burning, stinging, eye irritation, headache, and changes in taste. Eye infections can occur, especially if the eye drops are not used properly.

To use the eye drops:

1.

First wash your hands thoroughly. If you wear glasses or contact lenses, remove them.

2.

Tilt your head back, and with your eyes open, create a little pocket with your lower eyelid by pulling it away from the eye.

3.

Look up towards the ceiling, then squeeze the eye dropper gently to instill 1 drop into the pocket.

4.

Close your eyes and apply gentle pressure to the corners of the eyes at the bridge of the nose to prevent the medication from draining into your tear duct.

5.

Repeat with the other eye, if applicable.

6.

Try not to touch the tip of the eye dropper onto your eye or any other surface.

7.

For more detailed instructions, see the package insert for your particular medication or check with your doctor or pharmacist.

People with certain medical conditions should not use some of these eye drops. To ensure you are taking the most appropriate medication, inform your doctor and pharmacist of any other medications you are taking and of any medical conditions you have. You should follow your doctor's and pharmacist's instructions on using the medication to ensure you get the most benefit from it. If you are taking any of these medications and your allergy symptoms do not go away completely, talk to your doctor. Allergy shots Allergy shots may be needed when you are exposed to a lot of allergens (e.g., pollen, dust mites) that you cannot avoid, or when allergy symptoms are so severe that allergy medications can't control them. Allergy shots, or immunotherapy, are designed to desensitize your immune system to your allergy triggers or allergens. Allergy testing identifies these allergens. Allergy shots contain a very small amount of the allergen, and when you receive allergy shots, your body makes antibodies to the allergen. The next time you are exposed to the allergen, the antibodies block the effect of the allergen so that your symptoms are less severe. Over the course of your allergy treatment, your immune system builds up tolerance to the allergens. An allergist, a doctor who specializes in allergies, will determine the appropriate amount of allergen for the allergy shot. The dose is individually prepared using standardized extracts of the specific allergen. For example, if you are allergic to grass, then standardized grass pollen will be used to prepare the allergy shots. You need to get allergy shots about once or twice a week, over a period of several months. After about 3 to 7 months, your doctor may recommend that you start receiving allergy shots less often, called maintenance shots. Maintenance shots are given about once a month for 3 to 5 years. After this time, you may be able to stop having allergy shots. Another type of immunotherapy uses modified extracts of allergens. These allergy shots are given over a shorter period of time and need to be given every year. Pollinex-R® is a modified ragweed pollen that can be given to adults and children over 8 years old who have ragweed allergy. It is given before ragweed season (which usually starts in mid-August) and consists of 4 injections that are administered approximately 7 days apart.

Allergy testing and diagnosis Doctors may perform a few tests before diagnosing you with allergies. In order to rule out other medical conditions that may be causing your symptoms, your doctor will ask detailed questions about: 1.

Your symptoms, how often you experience the symptoms, and the severity of your symptoms

2.

your personal and family medical history

3.

how your usually treat your allergy symptoms

4.

what triggers your allergy symptoms

Your doctor may also perform a physical exam, where he will look at your nose and nasal passage. Your doctor may also suggest the following allergy tests:

1.

skin prick test: This type of test confirms which allergen causes the allergic reaction. In this test, a small amount of purified allergens are pricked into the skin of your arm or upper back. If you are allergic, a hive (a raised, itchy red bump) will appear at the test location on your skin, letting you and your doctor know which particular allergen you're allergic to. If you are scheduled for a skin prick test, you should stop using antihistamine medications 3 days prior to the appointment.

2.

allergy blood test: In this test, your doctor takes a sample of your blood and sends it to a laboratory, where the amount of immunoglobulin E (IgE) antibodies is measured. These substances are produced by your body in reaction to exposure to an allergen. This test, also called a radioallergosorbent (RAST) test, can measure your immune system's response to a specific allergen.

Allergy Skin Test

(Scratch Test, Skin Prick Test, Skin Patch Test)

Description of the test

View larger image An allergy skin test identifies which substance triggers an allergic reaction. A small amount of the substance, or allergen, is introduced to the body through the skin. If the skin reddens or swells then the test is read as positive and the person is probably allergic to that substance. The reaction is due to the release of histamine, a chemical naturally found in the body, which causes swelling, redness, and itching (also known as a wheal). This test is performed by an allergist.

How often should the test be performed? Your doctor will decide when and how frequently this test is required.

Why is this test performed? Allergy skin tests are performed to identify what allergen is causing allergy symptoms (such as sneezing, nasal congestion, itchy eyes, wheezing, skin rash, and swelling) so that people can avoid the trigger if necessary. There are many allergens - including foods, medications, and environmental substances (such as ragweed and fungus), as well as contact allergens which irritate the skin. Allergy skin tests take place when allergy shots are being considered. Testing may also be necessary for people with serious allergic rhinitis or asthma.

Are there any risks and precautions? Some people have extremely serious allergic reactions, called anaphylactic reactions. If a person has had an anaphylactic reaction to an allergen in the past, they may not have an allergy skin test for this substance as the test might provoke a dangerous reaction.

The most serious risk of having a skin prick test is anaphylactic reaction. This reaction is a medical emergency, causing difficulty breathing and a dangerously low blood pressure. However, anaphylactic reactions with skin prick tests are rare and the allergist will be monitoring you closely. Skin testing may not be performed if you have certain skin conditions, such as severe eczema or atopic dermatitis.

What happens during the test? There are three different types of skin tests. The first is called a skin prick test or scratch test. A small drop of substance is placed on the top of the skin. Then, the skin underneath the drop is pricked or scratched with a sterile needle to introduce the allergen to the top layers of the skin. If the area becomes red or swells, the allergy skin test is positive. If there is no reaction, the test is negative. The second test is called an intradermal test. A small amount of substance is injected into the skin to reach deeper layers of the skin. This test shows whether a person has antibodies to the allergen. The intradermal test is done when the skin prick test is negative but the patient is still thought to be allergic to that substance. The third test is the skin patch test. The substance is placed on a patch and the patch is placed on the skin for up to two days. This test shows whether a person develops contact dermatitis (rash), which is an allergic reaction on the skin due to direct contact with an allergen. Allergy skin tests are typically done on the back or the back of the arm, depending on the number of allergens being tested. If a person is being tested for several allergens, a grid may be used to separate the different substances from each other and keep track of them. A reaction can usually be seen within 15 minutes. The doctor may choose to do a blood test, called the radioallergosorbent test (RAST), with the skin allergy test. This test measures the levels of antibodies in the blood. The levels of antibodies may be elevated if a person is allergic to the substance. The RAST can also be done if a person cannot have a skin test.

How should I prepare for this test? There are no food or drink restrictions before going for an allergy skin test or a RAST. Your doctor may ask you to stop taking some medications before the tests, such as antidepressants or antihistamines which may affect the allergy skin test results. Antidepressants and antihistamines do not have any affect on a RAST. Tell your doctor or prescriber about all prescription, over-the-counter (non-prescription), and herbal medications that you are taking. Also tell them about any medication allergies and medical conditions that you may have. Ask your doctor or pharmacist whether you need to stop taking any of your medications before the test.

What can I expect after the test? If your allergy skin test is positive, you have several options to prevent an allergic reaction from occurring again. Some people choose to undergo desensitization, where small amounts of the allergen are gradually introduced to the body so that the person develops immunity to the allergen. If an allergic reaction develops, antihistamines can be used to relieve symptoms. Your allergist may also discuss helpful strategies to help you avoid or minimize exposure to allergens.

Results The skin prick test and intradermal test can be read within about 15 minutes and the allergist can tell you the result during that same visit. The skin patch test requires you to return to your doctor's office after having worn the patch for two days. At that point, your doctor can tell you the results. RAST samples are sent to a lab and may take one to two weeks before results are available.