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There's no end to my pain in the fall either. That's when ragweed allergies kick in. Like many Canadians, I am plagued with seasonal allergies (also known as allergic rhinitis) caused by breathing in airborne substances that are almost impossible to dodge.
Fellow sufferers know how unpleasant that can be. But even worse, allergic rhinitis is a risk factor for asthma – a potentially life-threatening disease. Unfortunately, the number of allergy sufferers has been rising for decades, according to Dr. Susan Waserman, a professor of medicine at McMaster University in Hamilton. An estimated one in four Canadians now lives with allergic rhinitis, and eight per cent of adults and 12 per cent of children have asthma.
The cause of this growing prevalence is the focus of plenty of research and debate. But one thing is certain: The trend seems to be happening particularly in the developed world, including North America and Europe. "As countries become more developed, allergies tend to rise," says Dr. Mark Larché, a professor of medicine at McMaster University and the Canada Research Chair in allergy and immune tolerance. What's more, he says, when immigrants from low-risk countries move to high-risk countries, their children tend to develop allergies. "There is definitely an association with the western lifestyle."
Your confused immune system
The most common theory about why our immune systems are out of whack: We're too hygienic. "I look at it from an evolutionary point of view," says Larché. "Human beings have been around for 100,000 years and we have evolved immune systems that live in parallel with all the bugs around us."
Over the past half-century or so, as modern medicine has beaten back bacterial, viral and parasitic diseases, our immune systems have been starved of "learning material," says Larché. The result: They may be unable to tell the difference between real threats and innocuous substances, such as pollen. "Our immune systems are perceiving threats where they don't really exist," he explains.
There's also a genetic component to allergies, says Waserman. "If both your parents have allergies, you have about an 80 per cent chance of developing them too," she says.
But, as Larché points out, people aren't born with allergies. The immune response doesn't seem to develop until age five or six, and may be triggered by a viral infection. "The theory is that the viral infection makes children's noses and airways inflamed," he explains. "If you have a good dose of the allergen at the same time, it gets tarred with the same brush."
Just to confuse matters further, climate change seems to be a factor. Although it doesn't cause allergies directly, several studies have confirmed that increasing carbon dioxide levels and rising global temperatures are driving the growth of the very plants that incite our sniffling. A 2011 study, for example, found that in some parts of North America, such as Winnipeg and Saskatoon, ragweed now sheds pollen for almost a month longer than it did in 1995.
Achoo! allergy or flu?
Doctors may not be able to pin down the exact cause of allergies, but they do have a good understanding of the mechanism behind allergic rhinitis. Ironic as it may seem, when you're sneezing, sniffling and wheezing, your immune system is actually trying to protect you. It's just being a little overzealous, mistaking harmless substances in the air for dangerous invaders, says Waserman. The immune system responds with a flood of chemicals – including histamine, bradykinin and leukotrienes – that dilates your mucous membranes, inflames your nose and throat, and causes your eyes to itch and water.
These symptoms often mimic those of a cold or flu, and it's easy for sufferers to confuse the two. But according to Antony Ham Pong, an allergist in Ottawa, there are two distinct factors that can clear up the mystery: timing and symptoms.
If you tend to get symptoms every year during allergy season, it might be a clue that you're suffering from allergic rhinitis rather than a cold, he says. "And if it's still going on â€¨after a week to 10 days, you know it's probably an allergy."
In addition, Ham Pong points out, "with a cold, your nose runs and you sneeze, but it doesn't cause the sneezing fits that you have with an allergy, like five or 10 sneezes in a row." Itchy, watery eyes and an itchy nose are also typical signs of an allergy, particularly in adults, whereas if you're achy, feverish or feeling generally unwell, you're likely suffering from a cold. Finally, he says, "with a cold, [nasal mucus] tends to be more green or yellow, â€¨as opposed to clear for allergies. The colour indicates infection."
The first line of defence
We know you're miserable. The bad news: As yet, there's no magic bullet for allergies. But there are treatments that can reduce the symptoms. Your first line of defence for intermittent seasonal allergies will likely be antihistamine pills. They block the histamines that cause sneezing, a runny nose and itching. "They can be used on an as-needed basis and they work within hours," says Ham Pong.
The good news: You can take nonsedating antihistamines for months or even years and they won't hurt you. But they do have a couple of flaws. Even so-called nondrowsy versions can have a sedating effect in some people. And you'll need a formulation that contains a decongestant to unblock your stuffy nose. The problem: Antihistamines that contain decongestants can aggravate high blood pressure and anxiety levels, and may cause sleeplessness.
If your allergies last for months, Ham Pong's treatment of choice is nasal steroids (not to be confused with over-the-counter nasal decongestant sprays). They reduce swelling, mucus production and nasal congestion, making your nasal passages less sensitive and less likely to react to allergy triggers such as pollen. "You can use them once daily and very little of the steroid is absorbed by the body, so there is no concern about steroid side-effects," he says. The downside: Treatment is available by prescription only, and it takes at least one day to start working and longer to provide the maximum effect. "It is best used daily and continuously during allergy season, or even year-round," suggests Ham Pong. While nasal steroids help control symptoms, â€¨they won't actually make you less allergic.
For that, the only real option is what doctors call "desensitization immunotherapy" (most commonly in the form of allergy shots), injections of minute amounts of an allergen â€¨to desensitize you over time. Not only can the shots alleviate allergies but they can also prevent you from developing new sensitivities and allergy-related asthma, says Ham Pong. "And the improvement can last for years after the shots are stopped." But the treatment requires more of a commitment than many allergy sufferers are willing to make, requiring regular visits to the allergist's office – initially once a week and then every three weeks for five years.
Next-generation allergy shots currently being developed promise to cut down on the number of injections needed and minimize side-effects, such as swelling, itching and (rarely) anaphylaxis (a potentially life-threatening allergic reaction). â€¨But they won't be available for several years.
For now, the latest spin on immunotherapy is a grass-pollen tablet called Oralair, released last November. It is taken once daily throughout pollen season. "It has proven to be quite effective," says Ham Pong.
However you choose to treat your allergies, don't wait until they're in full swing to address them. "People sometimes underestimate the effects of allergies," Ham Pong says, pointing out that, apart from making you feel miserable, allergies can take a toll on your ability to concentrate and get a good night's sleep. He recommends a targeted, consistent approach to keep them in check. "It's like snow tires," he says. "You leave them on for the season. You don't put them on for a snowstorm and then remove them once the snow is over."
|This story was originally titled "How to survive allergy season" in the June 2013 issue. |
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