For millions of Canadians, the end of winter is one of those good news and bad news stories.

The long, cold slog and all that sniffling and sneezing brought on by a never-ending string of colds going through the office or the kid's school is finally over — only to be replaced by all that miserable sniffling and sneezing triggered by trees and grasses coaxed back to life by ever-milder weather.

More than one in six Canadians suffer from hay fever, or seasonal allergic rhinitis. Depending on what a person is allergic to, allergy season can start in the early spring and last right through to the first killing frost of the autumn. In some parts of the country, you could suffer from March to November.

A survey commissioned by pharmaceutical giant Johnson & Johnson suggests as many as 10 million Canadians may suffer allergy symptoms and that more women than men admit to symptoms. The survey also found that 55 per cent of Canadians claim their allergies cut into their productivity and more than a quarter say they'll limit their outdoor time to prevent the onset of symptoms.

The survey found that Ontario suffered the highest rates of seasonal suffering while Atlantic Canada reported the lowest rates.

The allergy season got off to an early start in 2006, thanks to a milder than normal winter across most of the country and a warm spring. Pharmacists and allergists said more people than usual were seeking relief by early May.

And it seemed that almost as soon as the snow disappeared in most of the country in 2007, people were showing up at doctors' offices, looking for relief from sneezing, itchy eyes and a runny nose.

"As the spring comes earlier — and this year we had a very late fall — what's happening is there's lots of pollen, so people are getting allergies to the trees already," family physician Mike Evans told CBC News.

In Manitoba, conditions were ripe for a bumper crop of a fungus called "snow mould" in late March, one of the biggest contributors to seasonal allergies in the region.

Here are some frequently asked questions about seasonal allergies and what you can do about them:

Why do I start sneezing as soon as the weather starts warming up?

Blame your parents and your immune system. If both your parents suffered from allergies, there's a 66 per cent chance you will, too. If one parent had allergies, your risk drops — but only to 60 per cent.

Your immune system identifies and reacts to different allergens, such as pollen that's blown around by the wind. When an allergen enters the body of someone who is predisposed to allergies, it triggers an immune reaction and the production of allergen-specific antibodies. These antibodies migrate to mast cells lining the nose, eyes and lungs.

The next time a pollen particle drifts into the nose, mast cells release a slew of chemicals (histamines) that irritate and inflame the moist membranes lining the nose and produce the classic symptoms of an allergic reaction — scratchy throat, sneezing, itching and watery eyes.

Basically, your body is objecting to the sexual activity of trees (early to mid-spring), grasses (late spring and early summer), and ragweed (late summer until the first frost).

Or you might be sensitive to spores, which are the reproductive particles or seeds of fungi or moulds. Spores can cause even more problems than pollen in some people, because they are smaller and can get deep into the lungs and possibly trigger asthma.

In some cases, people who are allergic to birch and alder pollen can develop oral allergy syndrome. You may have this if you've noticed allergy symptoms after you've eaten an apple, plum, nuts, celery or carrots.

This cross-reactivity is believed to be due to the antigen (allergy-causing protein) structure of the pollen grains and the carbohydrate protein covering of the foods. Cooking or peeling the skin will usually help. That's why you might have trouble eating an apple but have no problem with apple pie.

Am I born with allergies?

No. You develop them after you are exposed to allergens. It usually happens during your first few years but it can happen anytime — even well into adulthood. Sometimes a child's allergy symptoms will diminish later in life, or even go away completely.

How do I know that my allergy symptoms aren't just a cold?

You can be pretty sure your hacking and sneezing are the result of an allergy if:

• There is no fever and no muscle ache.
• Mucous secretions are clear and runny.
• Sneezes occur in rapid, multiple sequences.
• Your nose, ears and throat (especially the palate or roof of the mouth) are itchy.
• Your symptoms last longer than the typical cold, which usually lasts seven to 10 days.

If you're still not convinced, your doctor can perform skin or blood tests to confirm whether you are allergic to something.

What can I do to reduce my exposure to the stuff that makes me so miserable?

There are a number of steps you can take, short of moving into a hermetically sealed chamber:

• Stay inside when the pollen count is high (especially between 5 a.m. and 10 a.m. when it's usually at its highest), and keep your windows and doors closed.
• Air conditioning can also help – but you must clean or change your furnace's air filter often.
• If you need to get out of the house on days when pollen counts are high or it's windy outside, consider going to air conditioned venues for your leisure activities.
• Wear a filter mask if you're going to be working around the yard.
• If you're driving, keep the windows closed and use the air conditioner.
• Keep your home as allergy-free as possible. Consider replacing carpets with wood or laminate flooring.
• Change your sheets and pillowcases often.

If you're a woman, consider having several children. An Italian study suggests the more children a woman has, the less likely she'll suffer from seasonal allergic rhinitis.

There's a theory that a small family size increases a child's risk of developing allergies because of the "hygiene hypothesis." It argues that fewer infections in childhood lead to increasing allergic sensitization, because the body does not have as much opportunity to build up protection against some antibodies. Without regular priming, the theory goes, the immune system gets bored and overreacts to pollens, or other allergens.

I'm not staying in all spring and summer. How can I treat my allergies?

Antihistamines. These pills contain drugs that are supposed to neutralize the histamines that are produced when allergens irritate your immune system.

Allergy pills have come a long way in the past 30 years. It wasn't that long ago that the only allergy pills on the market may have cleared up your symptoms, but left you so drowsy you couldn't function very well.

That type of pill is still on the market — and may be the best choice for some people. Newer allergy medications are less likely to make people drowsy. Some of them, however, can leave your mouth and your skin feeling dry.

In Canada, most allergy pills are available over the counter — you don't need a prescription.

If your symptoms are more severe, there are nasal sprays and eye drops you can also take. Several require a prescription.

Nasal sprays work by coating your nasal passages and protecting them from becoming irritated by allergens. However, these sprays must be taken well before allergy symptoms start for them to work effectively.

What about allergy shots?

This is another option, for some people. Injection therapy, however, has been shown to have little or no effect for about 30 per cent of allergy sufferers. As well, showing up for a shot once a week for three to five years is tough for a lot of people.

With allergy shots, you are injected with a small amount of the allergen once a week. The exposure is slowly increased until you build up a resistance to the allergen. Forty per cent of patients can expect excellent results.

Can allergies lead to more severe illnesses?

In some cases, severe allergic symptoms can lead to asthma. Asthma is a chronic inflammatory disease of the airways. The American Academy of Allergy Asthma and Immunology estimates that as many as 38 per cent of people with allergic rhinitis may also have asthma.

According to the 1996-97 National Population Health Survey, more than 2.2 million Canadians have been diagnosed with asthma by a physician (12.2 per cent of children and 6.3 per cent of adults).

The survey also found that asthma in children has become a bigger problem over the past 15 years. Asthma mortality rates increased from 1970 to the mid-1980s — especially for people aged 15 to 24 or over 65. By 1995, mortality rates had decreased to below the 1970 level — except among in the 15 to 24-year-old age group.

Hospitalization rates for asthma increased for children in the 1980s. By the mid-1990s, the rate had started to decrease but remained higher than the rate in the 1970s.

Asthma kills more than 500 Canadians a year and sends another 150,000 to hospital for treatment.