Ask Your Family Doctor

Developed by the College of Family Physicians of Canada

What causes allergies?

You have an allergy when your body reacts to things that don't cause problems for most people. These things are called allergens. Sometimes the term hayfever is used to describe a reaction to allergens in the air. Your body's reaction to the allergen(s) is what causes symptoms (see the box below).

Symptoms of allergies

	Runny nose
	Watery eyes
	Itchy nose, eyes and roof of mouth
	Sneezing
	Stuffed or plugged nose
	Pressure in the nose and cheeks
	Ear fullness and popping
	Dark circles under the eyes

Things that may make allergies feel worse

	Aerosol sprays
	Perfumes
	Air pollution
	Cold air
	Humidity
	Fumes
	Tobacco smoke
	Wind
	Wood smoke

What are the most common allergens?

Common allergens in the air are pollen, mold, animal dander and dust. Many other things, such as those listed in the box above, can make your allergy symptoms worse.

Pollen comes from trees, grass and weeds. Allergies that occur in the spring (late April and May) are often due to tree pollen. Allergies that occur in the summer (late May to mid-July) are often due to grass and weed pollen. Allergies that occur in the fall (late August to the first frost) are often due to weed pollen.

Pollen from flowers usually doesn't cause problems in people with allergies because the pollen is too heavy to float in the air. These plants rely on insects to carry their pollen.

Mold is common where water tends to collect, such as shower curtains, window moldings and damp basements. It can also be found on rotting logs, hay, mulches, commercial peat moss, compost piles and leaf litter. This allergy is usually worse during humid and rainy weather.
Animal dander is made up of bits of skin and hair from pets. Both are allergens. You can be exposed to dander when handling an animal or from house dust that contains dander.

Dust contains allergens, including dust mites. Dust mites are tiny living creatures found in bedding, mattresses, carpets and furniture. They like places where it's warm and humid. They live on dead skin cells and other things found in house dust.

How can I avoid allergens?

Pollens. Shower or bathe before bedtime to wash off any pollen and other allergens that may have collected in your hair and on your skin. Avoid going outside, especially on dry, windy days. Keeping the windows and doors shut can be helpful, as can using an air conditioner both at home and in your car.

Mold. You can reduce the amount of mold in your home by not having houseplants and by often cleaning shower curtains, bathroom windows, damp walls, areas with dry rot and indoor trashcans. Use a mix of water and chlorine bleach to kill mold. Repair areas as needed Don't carpet bathrooms or other damp rooms and use mold-proof paint instead of wallpaper. Throw away old books, shoes and bedding, which can be a source for mold. Lower humidity in your home by using a dehumidifier.

Pet dander. You may need to give your pets away or at least keep them outside because they bring pollen as well as animal dander in with them.
Cat or dog dander is often in house dust and takes four weeks or more to die down, so a short-term trial of no pet at home may not help you find out if this is a problem for you.

Dust. You can reduce dust mites by getting rid of the places where they like to live and breed, such as carpets, drapes and feather pillows, and by making your home less inviting by keeping low the humidity and dusting often with a damp cloth. See the box below for tips. Pay attention to keeping your bedroom clean. This is where you spend much of your time at home.
Wear a mask when you clean. Even better, have someone else at home clean for you or hire someone to clean.

Tips to reduce dust

	Remove drapes, feather pillows, furniture covered in cloth, Comforters you can't throw in the wash and soft toys.
	Replace carpets with linoleum or wood. Polished floors are best.
	Mop the floor often with a damp mop and wipe surfaces with a damp cloth.
	Vacuum weekly with a machine that has a high-efficiency particulate air filter (HEPA). Vacuum couches and chairs, and curtains as well as floors.
	Install an air cleaner with a high-efficiency particulate or electrostatic filter
	Wash carpets and upholstery with special cleaners, such as benzyl benzoate or tannic acid spray.
	Wash all bedding in hot water (hotter than 54°C [130°F]) every seven to 10 days.
	Don't use mattress pads.
	Cover mattress and pillows with plastic.
	Don't clutter.
	Lower the humidity in your home.

How are antihistamines used to treat allergies?

Please note: According to Health Canada (December, 2008) you should NEVER give over-the-counter medications, (like those described below) to children UNDER 6 years old.

If you do give these medications to children over 6 years old, be sure to measure the amounts very carefully. Follow the instructions on the package or bottle.

Antihistamines help reduce the sneezing, runny nose and itching of allergies. They're more useful if you use them before you're exposed to allergens.
You can buy antihistamines without a prescription. They are over the counter. They relieve symptoms and tend to have few side effects. For example, you may notice drowsiness and dryness in your mouth after taking them. This often improves after one to two weeks of daily use.

Nonsedating antihistamines are also on the shelves but sometimes you have to ask the pharmacist for them. These are less likely to cause tiredness or dry mouth, but they cost more and may also not require a prescription.

Some antihistamines are used as eye drops and nasal sprays. Ask your pharmacist for help when picking allergy medicine. Some antihistamines are no longer being used and some have precautions. Make sure you discuss what you're taking with your family doctor.

What decongestants may be helpful?

Decongestants help relieve the stuffy nose of allergies. They come as pills, nose sprays and nose drops. It's best not to use nose sprays and drops for more than three days because you can become dependent on them very easily. This causes you to feel even more congested when you try to quit using them than you did before you started.

You can buy decongestants without a doctor's prescription. Decongestants can raise your blood pressure, so it's a good idea to talk to your family doctor before using them. Many medicines combine both antihistamines and decongestants, use only what you need. It's best to avoid drugs that combine other drugs.

How can inhaled steroids help?

Inhaled steroids reduce the reaction of the nasal tissues to allergens. This helps relieve the swelling in your nose so that you feel less stuffy. They come in nasal sprays that your doctor may prescribe. You won't notice their benefits for one to two weeks after starting them. Inhaled steroids include, triamcinolone acetonide (an example is Nasacort) and fluticasone propionate (an example is Flonase).

Inhaled steroids aren't as likely to have side effects as steroid pills, but you shouldn't use the sprays or drops more than your doctor suggests. Your doctor may prescribe steroid pills for you to use for a short time if your symptoms are severe or if other medicines aren't working for you.

What are allergy shots?

Most allergies can be controlled by avoiding what triggers them or by taking antihistamines or other medications to prevent your body's reaction. Some people choose to get allergy shots. Allergy shots (also called immunotherapy) contain small amounts of allergens. They're given on a regular schedule so that your body gets used to the allergens and no longer reacts to them.

Allergy shots are only used when the allergens you're sensitive to are known and when you can't avoid coming into contact with them. It takes a few months to years to finish treatment, and you may need to have treatments throughout your life.

Severe allergy reactions. If you get severe life threatening allergic reactions, you should carry an adrenalin pen (Epi-pen) or Anakit. Talk to your doctor to see if you need something like this.

Revised 2007 The College of Family Physicians of Canada

This information provides a general overview on this topic and may not apply to everyone. To find out if this information applies to you and to get more information on this subject, talk to your family doctor. This health education material has been favorably reviewed by the Patient Education Review Committee of the College of Family Physicians of Canada: Dr Cathy MacLean, Halifax, NS (Scientific Editor) Dr C. Richard Fischer, Pickering, ON Dr Patrice Laplante, Fleurimont, QC Dr Richard Moffatt, Red Deer, AB Dr David Nunn, Kentville, NS Dr Cornelius Woelk, Winkler, MB The College of Family Physicians of Canada, one of the nation's largest medical groups, is committed to promoting and maintaining high standards for family physicians - the doctors who provide ongoing, comprehensive care for people of all ages. This patient education information was developed by The College of Family Physicians of Canada in cooperation with the American Academy of Family Physicians.

Support for this program has been provided by an educational grant to the Research and Education Foundation by Scotiabank.