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The Dose Transcript for May 15, 2025

Host: Dr. Brian Goldman

BRIAN GOLDMAN: Hi, I'm Dr. Brian Goldman. Welcome to The Dose. Well, it feels like seasonal allergies get worse every year, and I have to tell you, my itchy eyes this season feel itchier. And I've gone from two sneezes to five or more, which is apoplexy-inducing. And I'm taking a lot more antihistamine. So this week we are asking: why are my allergies getting worse? Hi Anne, welcome back to The Dose.

ANNE ELLIS: Hi Brian, it's nice to be here.

BRIAN GOLDMAN: Nice to be talking to you too. Are you a fellow sufferer?

ANNE ELLIS: I am indeed, so I have empathy.

BRIAN GOLDMAN: You have empathy and I hope you have remedies, which is why we're talking to you. But before we begin, can you give us a hi, my name is? Tell us what you do and where you do it.

ANNE ELLIS: Hi, I'm Dr. Anne Ellis and I'm Chair of the Division of Allergy and Immunology at Queens University in Kingston, Ontario.

BRIAN GOLDMAN: So how bad has this year's allergy season been thus far?

ANNE ELLIS: Honestly, Brian, we're just getting started. We've had a lot of starts and stops. We've had one or two nice warm days where you think, that's it, here it is, and yes, I'm sneezing, and then look at that, it's -2 in the morning, or cold enough that it shuts everything down, or it's raining. This past weekend has finally brought, I think, I predict -- once I look at my pollen counts a couple days from now -- the official start to the tree pollen season in a real robust way. At least in Kingston, Ontario.

BRIAN GOLDMAN: We're talking about this season's allergies, but we're also talking in more general terms. Are seasonal allergies actually getting worse?

ANNE ELLIS: Generally speaking, there have been some couple of years in the past few years where we've had a lot more pollen than we're used to seeing. It doesn't seem as be consistent. It's a bit annoying, 'cause it's harder to make better forecasts. But definitely last year's birch pollen season, and it looks like this year is going to be a doozy as well, has certainly been higher than we've seen in the past 10 years, for example.

BRIAN GOLDMAN: So what makes it a doozy? How do you measure a doozy?

ANNE ELLIS: [laughs] So it's when you go from zero to a hundred or more grains per cubic metre per metre in a couple of days. And it lasts. And we've had that now for two years in a row where it's been very cold winters, and then very slow to consistently warm up in a way that really gives that right nice signal to the trees that they should be doing something. And when it gets warm late, and that's what leads to those really booming pollen seasons like we've had for the past few years.

BRIAN GOLDMAN: Are more people experiencing seasonal allergies now than say 10 or 20 years ago?

ANNE ELLIS: If you go back to 20 years, absolutely. We've seen a fairly impressive rise in allergies generally in Canada over the past 40 to 50 years. It plateaued about 10 years ago, so it's not that we have any more people suffering from allergies, probably they're just noticing it more. Because we have had a little bit more robust seasons and more of an overlap in the spring. Like I said, we used to have a little bit more gradual lead in to springtime pollen seasons. Now they start late and they start with a whopper and you get both tree and grass pollen at the same time. That's been very consistent over the past 10 years. So that could be why it seems like more people are suffering from allergies. We're not getting that separation between tree sufferers and grass sufferers. They're all getting it all at the time.

BRIAN GOLDMAN: And I gather that for people who are allergic to more than one type of pollen, these overlapping seasons are going to result in a much more prolonged season of allergic symptoms.

ANNE ELLIS: Yeah, it ends up being overall a longer season and a bit of a double whammy, if you will. Because you don't get a break in between the two types of pollens that can be triggering symptoms. It makes the springtime the hardest of all, I'd say, for allergy sufferers.

BRIAN GOLDMAN: Let's talk about some of the reasons. What does climate change have to do with seasonal allergies?

ANNE ELLIS: Climate change has led to this shift in when we get spring and how we get spring. The fact that there has been a delay fairly consistently now in when we shift from winter to spring and spring to summer. And that spring to summer shift has gotten much shorter as well, as you've probably noticed yourself. And it just means that it changes how trees pollinate. It changes when the seasons start and stop and leads to things being different than they were 20 years ago, for sure.

BRIAN GOLDMAN: And does a longer growing season mean that we're going to have higher pollen counts?

ANNE ELLIS: Absolutely. Not so much, like, when you spread it out over the entire duration of the season. You get one or the other. Either it's short and intense, or it's long and drawn out. So, either way it all leads to more symptoms

BRIAN GOLDMAN: How long does allergy season typically last these days?

ANNE ELLIS: If you're living in Ontario, and you have tree, grass, and ragweed, which are the common, warm weather suffering, triggering things, tree pollen season starts, you know, usually now, 1st of May. Goes through to, you know, mid- to late June. Late May, early June is when grass pollen starts, and that goes through to mid- to late July. You have a bit of a reprieve in the middle of the summer before ragweed starts up almost like clockwork on August 15th, then goes through to the first frost in the end of the fall. Those of you who are listening in the Western provinces have the advantage of no ragweed, but you have a longer tree season. It started a long time ago compared to those folks in Ontario and Quebec, for example. So pretty much from the minute it gets warm and not snowing to when the snow falls is when we see that pollens are causing problems for people with allergies.

BRIAN GOLDMAN: So if pollen allergies don't usually kick in until later in spring, why do some people start experiencing allergic symptoms around late March?

ANNE ELLIS: That's typically from what we call snow mold. So when the snow melts but nothing's growing yet, and you look at your lawn and you see those areas of dead brown grass, that dead brown grass has been caused by snow mold that proliferated over the winter while it was covered in snow. And those spores get released as soon as there's no longer any snow on the ground to cover them up. So that can certainly trigger symptoms for those people who are allergic to mold. And also in March, when we're having less actual snow or slush on the roads and you get all that dried salt and sand from the winter, that gets stirred up. It can certainly cause a lot of irritant type reactions that feel like allergies, but are really just direct irritation to your nose and eyes, etc.

BRIAN GOLDMAN: Roughly what percentage of patients will be allergic both to mold and to pollens?

ANNE ELLIS: So we don't have great data on how many people are allergic to what specific things. We do know that 25 to probably 30% of Canadians suffer from allergic rhinitis or hay fever. And the majority of people who are allergic to one thing are at least allergic to one other thing, or we call them polysensitized. So 70 to 80% of people will be allergic to more than one thing if you were to skin test them.

BRIAN GOLDMAN: What parts of Canada do we typically see the worst allergy seasons?

ANNE ELLIS: Good old Quebec and Ontario, because we have nice robust summers with lots of trees and lots of pollen. But importantly, also ragweed. Come late summer, early fall we tend to get the biggest hits in terms of seasonal allergies across the country. Although the entire country is affected, just in slightly different times and in slightly different ways.

BRIAN GOLDMAN: I mentioned climate change. Is that the only factor increasing the duration and severity of allergy season for the people who suffer from it?

ANNE ELLIS: I think there has also been some evidence showing that CO2 concentrations can make pollen more allergenic and also more robust -- more likely to hang around, if you will. And plants will create more pollen under higher CO2 concentration. So that's an important consideration. The other thing is the way in which we're planting trees now. We're planting more male trees that are the ones that create pollen, as opposed to female trees, which are the ones that bear fruit. Because the ones that bear fruit make a bigger mess so city planners like male trees better, which means they're planting more pollinating trees. So we're getting more allergen in the air because of some of those city planning decisions in urban areas.

BRIAN GOLDMAN: So that means that people who live in cities may have more severe allergic symptoms simply because of the trees that are being planted in the city.

ANNE ELLIS: Yeah, they're not getting away from it just because there's less grass. [laughs]

BRIAN GOLDMAN: We can't change the climate. We can, I guess, change the kinds of trees that we have in cities, but how do we help people cope with raging allergy symptoms?

ANNE ELLIS: Well, we always say if you can avoid your allergen, that's optimal. Because if you don't come into contact, you won't have symptoms. However when it comes to springtime allergies driven by pollen, it's hard to not go outdoors. There are some things you can do though. So, keeping your window shut; using air conditioning and filters on your furnace, for example. But also things like not hanging your clothes out to dry so they're not getting covered in pollen. That's something that we recommend. Again, washing your clothes right after you come in from outside. Those sorts of things. But ultimately, people will turn to either their pharmacy or their physician to look for some of the therapies we have, which are safe and effective, fortunately. So, non-sedating antihistamines, nasal corticosteroid sprays, and we'll get into talking about immunotherapy, I'm sure, but at least we have lots of effective therapies that you can get either from your pharmacy or a prescription from your doctor.

BRIAN GOLDMAN: It's possible to make a decision to stay indoors on days when there is high pollen count, am I right?

ANNE ELLIS: Yes. It is a possibility, yeah.

BRIAN GOLDMAN: How do you do that? Where do you get that kind of information?

ANNE ELLIS: So in terms of looking to find out, is it a high pollen day? So your clues just from looking out your window are: is it sunny and is it windy? Those are the best indicators that there's probably lots of pollen in the air. Otherwise, you could in theory turn to the Weather Network or other channels like that. Unfortunately, they are no longer using data on pollen counts from Aerobiology, which is a company that actually counts the pollen at major centres all across the country. They have turned to AI to base the pollen counts on historical pollen counts, which may or may not be accurate for the day in which you're living in. So things to look for are: is it raining? Is it not windy? Those are likely your best days to go outside because there's less likely to have high pollen in the air when the rain is holding it down where it belongs and it's not windy, which is not blowing it around.

BRIAN GOLDMAN: Is there value in using face masks if you are going to go out on a day with a high pollen count? And if so, what kind of face mask?

ANNE ELLIS: Yeah, so this was an interesting finding that came out during the pandemic, actually, and people were wearing masks outside for the first time ever. We did realize that if you were wearing those medical grade masks, like we asked you to wear when you came into the hospital, for example, they did block the inhalation of pollen and other sort of particles, which makes sense. But it really did help reduce the amount of pollen that you breathe in. So that is a reasonable way to minimize your pollen exposure on an outdoor day.

BRIAN GOLDMAN: All right, let's talk about medications. Let's talk antihistamines because they're ubiquitous, they're easy to obtain. Which ones do you recommend?

ANNE ELLIS: You definitely want to look for ones that say non-sedating antihistamines. Once a day is a good clue that it's a non-sedating antahistamine. The older sedating antihistamines like Benadryl that people are familiar with, unfortunately, we have realized for many years, and increasingly we're able to get that message through to the public, that these are really not safe antihistamines to use. And they're not all that effective. The side effects, the data profile is an issue with those older antihistamins. They don't work as well for allergic rhinitis anyway, they wear off fast. So it's much better to use the non-sedating antihistamines like Cetirizine, Desloratadine, Loratadine, Fexofenadine. But essentially, ask your pharmacist for which ones of these are second generation or non-sedating antihistamines. Those are the safe and effective options you want to choose from.

BRIAN GOLDMAN: And are these all over the counter, or are there prescribed non-sedating antihistamines as well?

ANNE ELLIS: Yeah, we have three different non-sedating antihistamines that can be prescribed by your physician. Rupall or Rupatidine, Blexten or Bilastine, and there's a high dose of Reactin or Cetirizine that can be covered by a drug plan if you're fortunate enough to have one.

BRIAN GOLDMAN: You mentioned corticosteroid nasal sprays. What can you tell us about those?

ANNE ELLIS: Just to first and foremost, make sure that people are aware that those nasal sprays are not designed to work instantly. They are meant to be used on a regular basis throughout the season to provide your maximal benefit. They are safe. They are steroids, but they're low dose steroids that don't get past the nose. So it's not like, you know, some of the side effects you may have heard of from steroids generally. But they are very effective in reducing nasal congestion in particular, which you may not find antihistamines do the trick for you. And when used properly, they're very safe, and especially if you use-- you can use them throughout the entire season without difficulty. And I have patients who have year-round allergies who use these nasal sprays all year round without any issues, so. The key is to just make sure that you're, one, pointing that device towards your ear when you're spraying that into your nose. Don't put it up and down or worse, don't put it towards the middle of your nose. Because then, one, the medication isn't getting where it needs to go. Two, you're more likely to have side effects like nose bleeds, nasal dryness and headaches. So when you put the pointer in, angle it towards your ear, and then spray down to get the delivery of the nasal steroid spray that's in it.

BRIAN GOLDMAN: Are there any risks in using antihistamines or nasal sprays on a long-term continuous basis?

ANNE ELLIS: If you're using those second generation newer antihistamines like I mentioned or the nasal steroid sprays, as you're using them as prescribed, there are no significant risks to long-term use. That's not the case of those older sedating antihistamines though, that have been described to have some fairly impressive side effects and long-term consequences if used regularly on a long-term basis.

BRIAN GOLDMAN: Such as?

ANNE ELLIS: Antihistamines like diphenhydramine, which is what's in Benadryl, has been associated with dementia when used long term. And certainly, we know if the elderly use those first generation sedating antihistamines, it can cause delirium and cognitive difficulties. So again, when we have these safer, newer options, particularly when things like Rupall and Blexten are available by prescription, we have so many better, safer, effective ways to treat allergies than those older sedating antihistamines.

BRIAN GOLDMAN: If you take one of those non-sedating antihistamines every day for, say, 5 or 10 or 15 years, will, will that have any effect on your immune system and your ability to respond to allergies?

ANNE ELLIS: Certainly medications like an antihistamine don't lose their effectiveness just because you use them day in and day out for years and years on end. Sometimes patients have reported to me that they feel like it's not working anymore. Chances are good that that means you need to move on to something beyond an antihistamine. But certainly it's safe to take an antihistamine on a daily basis all the way through the year if you need to.

BRIAN GOLDMAN: When I was a child, I had a seasonal cough every September and I ended up having allergy shots as a kid. How effective are they?

ANNE ELLIS: Old school allergy shots, very effective. The downside is, of course, as you know, Brian, they require an injection and they require weekly visits to the doctor's office. But for the treatment of environmental allergies of any kind, very effective. Basically, we retrain your immune system to ignore the things you're allergic to rather than continuing to have allergic reactions to them. So the way in which we used to do this for everyone was a series of weekly injections or buildup over the course of six months, followed by monthly injections thereafter for usually a typical course of five years to produce a long-lasting change in your immune system. Now, however, we have sublingual immunotherapy tablets. So these are tablets that just dissolve under your tongue and are also specific to the things you're allergic to. So for you, Brian, I would guess if it was every fall, it was probably ragweed that was getting you. So you would take a tablet now, starting in April, every day through to the first frost, and then you'd stop and start that back up again the following spring. And that would very much improve your need for medications and symptoms you would experience during ragweed season in that September month.

BRIAN GOLDMAN: That's interesting. So are you finding that more patients are opting for tablets under the tongue instead of needles these days?

ANNE ELLIS: It's really improving access to immunotherapy and that disease modifying option, because the tablets are much more palatable than weekly trips to the doctor's office for an injection, and has really opened up the ability to really get definitive relief for allergy symptoms. So I definitely am prescribing much more immunotherapy in total, but particularly, I'd say at least half of my practice has switched to tablets as opposed to injections.

BRIAN GOLDMAN: And are they approved for patients of all ages?

ANNE ELLIS: Yes, that's the exciting thing. Just last week, the final one fell into place so that all the tablets we have in Canada that are available to treat birch, grass, ragweed, and house dust mite are now approved for ages five and up. So, accessible to essentially all ages.

BRIAN GOLDMAN: And how expensive are they?

ANNE ELLIS: The answer will depend on which province you're in and what kind of drug plan you have. The price per tablet all-in, out-of-pocket cost is approximately $5 a day. However, the company who makes this product does have a fairly generous patient support program if you need to have some of that covered. And also some of them are covered by some provincial formularies. So ask your specialist about all the various options to help get those covered.

BRIAN GOLDMAN: But clearly, five bucks a tablet for half a year could be quite pricey for a lot of Canadians.

ANNE ELLIS: There's no doubt that it could be for some Canadians. So again, always worth having a conversation about the various options that are there to try to help offset those costs.

BRIAN GOLDMAN: And if you have an employee drug plan, then there's a good chance it's gonna be covered?

ANNE ELLIS: Yes, that's correct.

BRIAN GOLDMAN: What can you tell us about Xolair and its potential use in treating seasonal allergies?

ANNE ELLIS: Xolair -- the generic name is omalizumab -- is a monoclonal antibody -- which is what we refer to as a biologic therapy -- that targets IgE, which is an allergy antibody, if you will. So IgE is the antibody in our immune system that's responsible for all the allergic reactions that we experience. Xolair's been on the market for, believe it or not, 25 years now, as a treatment for allergic asthma. Been very effective in reducing exacerbations or reducing asthma attacks in patients who suffer from allergic asthma. But it also helps for regular routine allergies. Not only allergic rhinitis -- it's, quote unquote, "not indicated for that" -- but definitely my patients who have allergic asthma and allergic rhinitis have noticed a huge improvement in their hay fever symptoms while they're on Xolair. In the United States, it's also indicated for food allergy, which it doesn't have that indication for it in Canada. But often people will ask me about that medication in the context of their food allergies. And so we have a bit of a discussion about things that we can and can't expect from something like Xolair for allergies generally. But I certainly can tell you it's very helpful for patients with allergic asthma, and it does help allergic rhinitis. If you happen to have both, then it's easier to get access to a medication that's designed for asthma, off the bat, let's put it that way.

BRIAN GOLDMAN: And you'd end up taking one injection prior to the allergy season?

ANNE ELLIS: Oh, unfortunately, no, it doesn't work in that way. Xolair is a once a month injection, and you would take it year-round. There is one study that was done giving it pre-seasonally for the so-called September spike of asthma in children. But unfortunately, it doesn't have that indication in Canada, so it would be hard to prescribe it that way.

BRIAN GOLDMAN: I would gather that this would be a considerably more expensive medication than the tablets that you place under your tongue.

ANNE ELLIS: That's correct. Yeah, it depends on -- the dose of Xolair is dependent upon your level of IgE in your blood, and your weight. But ranges from 15,000 to $37,000 a year depending on what your dose is, so. Definitely the tablets are a less expensive way to go if you're looking at something where you'd be paying out of pocket.

BRIAN GOLDMAN: Boy, you know, for a topic that has been around for a long time, it seems as if there's a lot of exciting developments in the treatment of seasonal allergies. Let's hope that your research can go a long way to reducing the suffering of people like me with seasonal allergies. And Dr. Anne Ellis, I wanna thank you for coming back on The Dose to talk about this broadly popular topic, especially nowadays.

ANNE ELLIS: Pleasure as always. Thank you, Brian.

BRIAN GOLDMAN: Dr. Anne Ellis is Chair of the Division of Allergy and Immunology at Queen's University's Department of Medicine. Here's your dose of smart advice. Seasonal allergies are getting worse in Canada and around the world. That means longer allergy seasons and more severe symptoms. One reason is that climate change has led to warmer temperatures and longer growing seasons. These extend the time that pollen is in the air. Warmer temperatures throughout the year lead to an earlier start to allergy season. In addition, increased atmospheric carbon dioxide associated with climate change leads plants to produce more pollen as well as pollen that is more potent. We used to have distinct allergy seasons brought on by, for instance, pollens produced by trees, grass, and ragweed. Now these distinct seasons tend to overlap, making it seem as if it's all one lengthy period of symptomatic misery. Urban planning is another factor. City planners have long recommended planting pollen-producing trees rather than messier fruit-bearing trees, further contributing to higher pollen levels. The symptoms of seasonal allergy haven't changed, although they may be more severe. They include nasal congestion and post-nasal drip; sneezing; itchy eyes, nose and throat; fatigue; cough and wheezing. Allergies are affecting more people than ever, so much so that the World Health Organization has recognized seasonal allergies as a global health issue. To minimize symptoms, stay indoors when symptoms are severe, such as when it's windy and raining. Reduce your exposure to pollen by closing windows at home and in the car. If you must go outside on heavy pollen days, wear a hospital mask. Effective treatments include prescription and non-prescription antihistamines, nasal corticosteroids, and decongestants. Allergy shots are a form of immune therapy in which you are given injections of pollen extract, beginning with a small dose and gradually increasing over three to five years. The shots condition your immune system to make antibodies that block the production of other antibodies that trigger allergies. Immune therapy can also be taken in tablet form that is placed under the tongue once each day, beginning before the pollen season and continuing until the season is concluded. Omalizumab, or Xolair, has shown promise in treating seasonal allergies, particularly seasonal allergic rhinitis or hay fever. The downsides are that the medication is expensive and must be taken continuously to reduce allergy symptoms. If you have topics you'd like discussed or questions answered, our email address is thedose@cbc.ca. If you liked this episode, please give us a rating and review wherever you get your podcasts. This edition of The Dose was produced by Sameer Chhabra. Our senior producer is Colleen Ross. The Dose wants you to be better informed about your health. If you're looking for medical advice, see your health-care provider. I'm Dr. Brian Goldman. Until your next dose.

Why are my allergies getting worse? - Transcript

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