265: Problem with Antihistamines That No One Tells You w/ Dr. Chris Thompson, MD

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Itchy eyes. Sinus pressure. Coughing and sneezing… Many people take antihistamines to get through an allergy episode, and that can be totally OK. But what about if you have to take them everyday? Are there potential long term side effects?

Today's guest, Dr. Chris Thompson, is a Board Certified Otolaryngologist, Head & Neck Surgeon with over 25 years of experience practicing medicine in Texas. He earned his undergraduate degree in Biomedical Engineering from Texas A & M University in College Station and went on to receive his Doctorate of Medicine at the University of Texas Southwestern Medical Center in Dallas. Dr. Thompson completed his residency with the Department of Otolaryngology, Head & Neck Surgery at the University of Texas Medical Branch in Galveston.Dr. Thompson focuses solely on allergy, sinus and nasal treatment and is considered an expert in all three fields. He is one of a handful of doctors that played an integral role in the development of the cutting-edge sinus procedure, Balloon Sinuplasty. Dr. Thompson is also experienced with nasal reconstructive procedures and rhinoplasty. He is very excited for the future of allergy treatment through sublingual immunotherapy, as more patients choose and stay consistent with the treatment.

He is also a member of the American Academy of Otolaryngology-Head & Neck Surgery, American Academy of Facial Plastic & Reconstructive Surgery, Texas Medical Association, and Travis County Medical Society.

Join us as Dr. Thompson discusses all things relating to allergies, the side effects of long-term use of antihistamines, and other options that people can use or try to get off of those meds such as immunotherapy.

Have you used antihistamines to calm down a severe allergic response? Have they helped, but you're ready to try something new? Let me know in the comments if you have questions!

Or, listen on your favorite app: iTunes (Apple Podcasts) | Spotify | Stitcher | TuneIn | Subscribe on Android

In this episode:

  • Are antihistamines appropriate for daily use?
  • Different types of antihistamines (what do they do?)
  • How eczema, food allergies + asthma are related
  • Antihistamines crossing the blood-brain barrier (YIKES)
  • Non-pharmaceutical options to consider (and discuss with your doctor)
  • Treatment options for different types of specific allergies


“There are some studies that link long-term antihistamine use with things like dementia. There was one I read recently that showed an increase in glial tumors, which are typically brain tumors… There are links to depression. There are links to weight gain with these and all, but one of the antihistamines over-the-counter can cross the blood-brain barrier.” [4:16]

“One of the most surprising facts about allergy is that only 2% of the population of allergy patients seek allergy care. Imagine, if 3% of cancer patients or 2% of sleep apnea patients sought and received proper care for their medical ailment? It would just be unfathomable, but yet in the allergy world, again, we're not talking about a life threatening problem in most cases, but it really does get sidelined and poo-pooed by a lot of doctors.” [25:20]


Find Dr. Thompson online

Follow Aspire Allergy on Instagram

Healthy Skin Show ep. 248: Is Eczema Related To Histamine Intolerance? 

Healthy Skin Show ep. 164: Mold Illness vs. Mold Allergy w/ Dr. Kasey Holland

Healthy Skin Show ep. 037: Nickel Allergy And Eczema w/ Dr. Peter Lio


265: Problem with Antihistamines That No One Tells You w/ Dr. Chris Thompson, MD FULL TRANSCRIPT

Jennifer Fugo: Hi, Dr. Thompson. Thank you so much for being here today. I'm excited to have you here on the show.

Dr. Thompson: Yes. Thanks, Jen. I'm excited too. It's great to be with you.

Jennifer: So I wanted to talk to you because I was surfing around Instagram, and I saw this amazing short video that you made talking about antihistamines. And I think a lot of my listeners, not all of them, but some of them are on antihistamines or have been prescribed antihistamines, or maybe they started taking over-the-counter antihistamines because they struggle with allergies and itchiness and hives. And even they're used sometimes with eczema.

And so the reason that your video caught my attention was because you talked about almost like a cautionary tale around antihistamines like, “Hey, we use them, but we need to be cautious and mindful because there are some consequences that people don't realize.”

So before we dive into that, because guys, we're going there. We're going to talk about that today. I want to just set the stage, what are antihistamine drugs and why do they oftentimes get used or prescribed, because you're an allergist and you have this vast knowledge and experience. So I'd love to hear from you, what is the purpose of these medications?

Dr. Thompson: So, the basic kind of mechanism of allergy is that something like a pollen or a pet dander enters your nose and sets off a chain reaction of chemical mediators that ultimately results in you being stuffy, you being itchy, feeling tired and all of the symptoms that we know so well, your eyes are itchy.

So, one of the major chemical mediators that is a part of that is histamine. So it's a great target for us in the allergy world to suppress. But histamine is a naturally-occurring chemical mediator and it does a lot of good things too. It's used throughout the body. And so it isn't something that you want to suppress entirely all the time, but it is helpful if you can reduce histamine when you're having an allergic episode, because it can help reduce your symptoms.

And most of your allergic patients have probably tried the variety of antihistamines, Allegra, Zyrtec, Benadryl. I mean, they're commonly sold over-the-counter. So they're well known.

Jennifer: And I find too that some of my clients, especially those who have severe hives, they will end up sometimes on multiples of these. So I've even seen clients on an H2 blockers. So something like famotidine, used to help kind of control stomach acid. And then they're on Zyrtec and something else. When you're using combos of these medications, is that usually for more severe cases?

Dr. Thompson: It sure is, yeah. Especially when you're trying to suppress both H2 and H1. So the H2 blockers that we all know of as acid reducers are also really antihistamines. So you can get more blockade by using that. So if you have a really severe patient like with hives, which is very difficult to treat, you can add in that H2, if your H1s or multiple H1 like Zyrtec and Xyzal and things aren't working, you can add in an H2 as well.

Jennifer: Okay. And so, in reality, people seem to end up on antihistamines endlessly. Not everyone, some people take them seasonally and then allergy season ends and they're fine for a while until it restarts again. But for those who are taking them long term, is that okay? Is that really just like safe to just do endlessly?

Dr. Thompson: Well, of course, the question is unknown. What really the downsides are, but there are some studies that link long-term antihistamine use with things like dementia. There was one I read recently that showed an increase in glial tumors, which are typically brain tumors. That was a Benadryl study. There's links to depression. There are links to weight gain with these and all, but one of the antihistamines over-the-counter can cross the blood-brain barrier.

So although they may not be as sedating as Benadryl is, or some of the older antihistamines, the fact that they still cross the blood-brain barrier always concern me for long-term use because like you say, a lot of people take it when they have their allergy symptoms. And that's probably fine to do that intermittently.

But we see so many patients who get started on these medications and then just take them every day because they might be working, they might be preventing. You'll often ask these patients, “Well, do you really get benefit from that medicine that you take every day?” And the answer is always, “Well, I'm not sure I just take it every day just in case. And when I have my allergy symptoms, they usually overwhelm that medication, but I'm thinking it's helping a little bit. So I just take it every single day.” And it's cheap. It doesn't really have any obvious side effects. So people kind of feel pretty safe with those.

Most of them don't even visit with their doctor about it. They just get them over the counter and then they just take them. And ultimately, when they come in and see us in an allergy setting, we start reviewing these things and then talking about alternatives, because I think most people think that's all there is. It's, “I have allergies. So I take Zytec every day and I'm pretty sure that's all I can do about it.” They just don't know there are other alternatives.

Jennifer: Is there any red flags in terms of like, because you did mention people will take these over the counter. They might not even discuss it with their doctor because they're just so well-known. It's sort of like you take acetaminophen for a headache. You take an NSAID for shoulder pain. You just do these things and you don't think anything of it. Are there any risks as well as mixing these medications with other medications that people might not realize?

Dr. Thompson: Well, especially the more sedating antihistamines can be a problem with other medications that might sedate you. And one of my concerns is that there have been studies that show sedation and decreased motor skills on driving tests for these, even the non-sedating antihistamines, the ones that cross the blood-brain barrier like Zyrtec that are considered non-sedating, but they still can have an impact. And they may have an impact almost at a subconscious level, whereby your motor skills might be delayed just a few milliseconds, nothing that you would call attention to during normal activities.

But the fact that somebody might be giving their kindergartener these medications all the way through high school makes me a little bit concerned about, okay, well could this have any impact on their ability to learn? Are they having any subclinical sedative effects for these things?

And then of course, if you add other medications that might do that, that would definitely make it worse. But that's my biggest concern is that they may be taking a medication as a child that could be impairing their performance. And they're just taking it endlessly without really measuring the response. Is the medication even helping?

You could make an argument, well, my child's miserable if they don't take it. But I find a lot of patients aren't even sure that it's making a difference until I say, “Hey, why don't we do this? Why don't you go off for a week or two, see how you feel. And then you can go back on and see.” And in many, many cases, they don't really notice much difference unless they're in a heavy allergy season and then they might get some improvement in their symptoms.

Jennifer: I wanted to circle back for a moment. You mentioned twice about the blood-brain barrier. And if someone is like, “The what?”

Dr. Thompson: Yes, okay.

Jennifer: What does that mean? Could you explain that?

Dr. Thompson: Yeah. So there are certain chemicals that can leave the bloodstream and enter into the brain. But there's a barrier there. There's a very important filter that doesn't let anything go in and out, whereas most of the body doesn't have that sort of barrier. Things can move freely between the blood vessels to the organs. But the brain is protected by this thing we call the blood-brain barrier.

So certain things can cross it and certain things can't, and the older antihistamines crossed it heavily and caused sedation. The newer antihistamines can still cross it, but they don't seem to have the same level of sedation. So it makes you concerned, “Okay, well, it's still entering the brain, but yeah, you're not obviously sedated. But does that mean it's okay?”

And I think it's probably okay in small quantities intermittently, but using it every single day is what concerns me.

Jennifer: So in talking about quantities, you just mentioned that which I think is important. So what do you, as an allergist, because you're not speaking for all allergies, you're just speaking for yourself. What do you consider appropriate or safe for someone in terms of use? Is it okay to use an antihistamine every day for, I don't know, a week or three months or five years? Is there any red flags in here that maybe we should start going, “Hold on, what's going on here?” And should we start investigating other options?

Dr. Thompson: Yeah. So I think if you are that allergy sufferer that has a couple of bad seasons, let's say, well, right now we're in oak season in Texas and it's miserable right now. And maybe that's going to last for six weeks, four weeks. If you have to use antihistamines intermittently when the levels are really high during oak season, and then maybe in the fall, you have some ragweed issues. I think that's fine. I think that you're, I don't believe there are probably any real long-term issues with taking those.

But if you are having symptoms most of the year, and I think as my patients get younger, I get more concerned about this because they're going to be taking it for longer and longer. And I worry about the impact on learning. If you're doing it more than a few weeks out of the year, that gets my attention. And so not just do I worry about the medications, but I think we can do better than that. I think we can make your symptoms better if we approach the problem a little more holistically.

Let's look at everything available to you because so few people know what is available to them in the allergy world. They really get tunnel vision. They get locked in on antihistamines and really think there's nothing else out there.

Jennifer: And I just want to ask, because I know it's not an antihistamine, but are steroids also used to help manage where you have this crazy histamine exposure? Is that one of the other tools in the toolbox?

Dr. Thompson: Yeah. Steroids are wonderful, but also in short-term therapies in the minimal doses that you can get improvement with. But if we have a patient who comes in … I have many patients who might be in elementary school and they come in, their eyes are swollen shut during allergy season. I mean that poor kid needs something and often a steroid burst pills by mouth typically will completely eliminate that problem for the time being. It's not going to last long, but it'll get them through that really severe episode.

But yeah, they're a great option used sparingly for obvious reasons.

Jennifer: Yeah. And also too, you want to be cautious of the length of time. That's just been my experience and everything. Even my dad, my dad told me when I started using steroid cream for eczema, he's like, “Listen, this is not a long-term solution. Be cautious of how much you put on. Be very sparingly, try and go the longest period of time without using it.” He warned me, whereas I feel like a lot of people don't get that warning. So it's good for people to hear that.

So if this is the toolbox that people mostly know of, what are some of the other tools that you, as an allergist, could possibly start to gravitate toward if you do want to get somebody away from using one, two, three antihistamines daily.

Dr. Thompson: Yeah. Well, you mentioned steroids and we were talking about steroids that are considered systemic, meaning it goes through your whole body, an injection into the muscle or a steroid that you might take by mouth. But there are also nasal steroids that you can apply topically to the nose. There are steroid creams that you can apply to the skin.

But for the topical nasal steroids where you really don't get much, if any, absorption into the system, you can kind of get the best of both worlds because you get a pretty potent medication, but you don't get systemic exposure that will give you those long-term side effects that steroids typically are known for.

Steroids, just like histamine, are naturally-occurring compounds in our body. We make steroids. And if your body is receiving outside steroids, then your body says, “Oh, I don't really need to work so hard.” And you stop making them. And that becomes a real problem.

So if you deliver steroids in the nasal root, like Nasacort, Nasanex, Flonase, which are all over-the-counter nasal steroids, you can kind of put a blanket of steroid in the nasal lining, which protects you from allergies to a certain extent without getting the systemic exposure that you would in a pill or an injection. So that's probably the easiest next step.

If you're needing antihistamines every single day, you should definitely try the nasal steroid because you'll probably get better relief. They are more effective. And again, I think-

Jennifer: And there may be some individuals. I know we have people who listen to the show who have had that reaction you've talked about with steroid exposure, who will definitely not want to try that. And that's okay. And so I know too, and before we were even started talking today, you had mentioned that there's this whole other avenue of possibilities that people, a lot of times blow off, ignore, don't know about or think it's kind of woo-woo and doesn't have much science behind it that I think would be of value for them to hear about. Would you mind sharing a little bit about those types of therapies?

Dr. Thompson: Yeah. Sure. So once you get to that point where you're taking the steroids, you're taking the antihistamines. You're just not really feeling that good or you're doing it all the time, and you just want an alternative or you're not a big fan of steroids, or you don't want to take a pharmaceutical every single day forever. Those are the patients that typically come in and see us, and our kind of mechanism to evaluate them is allergy testing.

We want to find out, “Okay, well what are you allergic to? And how serious is this? How, how severely do you react to these pollens?” If you're allergic to oak pollen, we can do a test in the skin or in the blood to find out whether you are or not. And then once we know what you're allergic to, we can prescribe a therapy that is almost like a vaccination.

It doesn't use any pharmaceutical. We use the actual pollen or the pet dander that you're allergic to. And we give that to you on a regular basis. When your body sees those things regularly and in high doses, let's say you're allergic to oak and you get oak pollen every single day or once a week through an injection, your immune system will begin to ignore that protein, that pollen, that enters through the nose.

And so in doing so, we can make you non-reactive to those things that are really bugging you. And we haven't used any pharmaceutical. So it's obviously safe for long-term use. And we treat for a period of time. Traditional allergy therapy is about five years and after five years, our expectation is that you're no longer reactive and you don't need any more therapy so that you're not having to take these medications for the rest of your life.

So that's kind of where that border is. If you're one of those patients you're taking these meds all the time, you're just not getting that grade of relief. It's really time to look at something that's a little more curative than the band-aids that the over-the-counter medications are.

Jennifer: And with these immunotherapy-type treatments, which this is really cool that you could essentially almost train your immune system to calm down.

Dr. Thompson: That's right. That's exactly what it is.

Jennifer: We were like, “Hey, you don't need to get in such a tizzy. Let's calm it down. You don't need to react. It's all right.” You mentioned pollen and dander. What about like food allergies or chemical allergies? Can you also use immunotherapy for those?

Dr. Thompson: So food allergies, absolutely. And we have a very large food allergy program whereby, and it's mostly children that we treat mostly with nut allergies, because these are kids who might be in the emergency room a few times a year. I mean, imagine being a parent of a child who has such a severe reaction, they land in the emergency room and you'd be living life on edge.

So we can train those children's immune systems to tolerate the nuts or whatever they're allergic to through a program by which they're treated weekly with small doses that are escalated. So we start small, so we don't create a reaction. And then we slowly increase that dose as the immune system learns to avoid a reaction to it.

Now with chemicals, that's much more difficult. First of all, the testing process is not as robust. So it's hard to actually identify them. There's so many different chemicals and combinations of things. We pretty much practice avoidance when it comes to those. But food and airborne or environmental allergies are actually really good at treating.

Jennifer: So I have a couple of things in my head. What about mold? If you're allergic to mold, would this be another option?

Dr. Thompson: That's right. So mold is part of that environmental allergy paradigm that we treat, and molds are a little more stubborn. They are a little bit more difficult to treat, but we can treat them in the exact same fashion. We test for them in the same fashion and they're easily identified. And they're tougher because they don't come on a schedule.

You know when your ragweed is going to hit you, we have cedar in the winter here in central Texas, but molds sometimes when it rains, they're high. And then I've seen dry summers where the mold levels were high too. So they're hard to identify, but they're easy to test for.

Jennifer: And then what about if someone has an allergy to a metal? I have one client that's alerted to cobalt. Other clients who have nickel allergies. Is there any, like what, what is the general thing you do with that? Can you do immunotherapy or is it more avoidance?

Dr. Thompson: Yeah. It's strictly avoidance for those things. We can test for it. You can do patch testings, but yeah, there isn't really a pathway through the immune system that we can treat those things yet.

Jennifer: Yet.

Dr. Thompson: That's right.

Jennifer: I think about all the amazing things that we will have available to us in the next 10, 20, hundred years. So I always like to go-

Dr. Thompson: That's right's. It's always changing. I mean, just over my career, I can't believe the things that we're doing now that we didn't even think of in the '90s and '80s.

Jennifer: Yeah. It is really, really amazing. I wanted to ask just for the moms out there, if they start to have this concern that they have a young child, so say maybe like a one-year-old or two-year-old, really young and they seem to be having these reactions to things, like different foods and such. Is it best to get that identified or is it okay for them to just give their child an antihistamine?

What do you think is kind of the best thing to do? I know you're a parent. So as a parent and as a doctor, what would you suggest?

Dr. Thompson: Well, I have a good answer for that because I have a child who went through that. And this is something I'm really passionate about because I watched her allergic … We call it the allergic march. The young kids usually start out with eczema. That's kind of the first step. And you might see that early on.

My daughter started demonstrating eczema probably at about six or eight months. And it got progressively worse. We did do allergy testing at about 18 months, which is pretty young, but because the immune system is developing and you're trying to hit a moving target. So they may be allergic to things that you see on a test at 18 months. And then at three years, they may have a different pattern. They may have added new sensitivities.

But a child who has eczema is very likely to go on to allergies, pollen, mold, pet dander, and then much more likely to develop asthma than a child who does not have the allergies. So that's a biggie in my mind because if you just treat with over-the-counter medications or your pediatrician is not pursuing any sort of specific allergy testing, then your child is much more likely to develop asthma and you can intervene at these ages and reduce that likelihood.

And I think if parents knew that they could actually decrease the likelihood of their child developing asthma, it's just a no-brainer. They would all choose that pathway. But people don't know this. And I see it time and time again. Even among physicians that they just don't know about that link, which is very clear cut nowadays, the eczema-allergy-asthma link. And if you get in there and interrupt it, you can really help these kids.

Jennifer: Yeah, absolutely. Well, I'm glad that we were able to touch on all age groups here because it's important. We have moms that listen to the show, and dads and grandparents listening for the little ones. And then we've got adults listening for themselves or their spouses or friends or whomever. It's just a wonderful community. And I'm so glad that we were able to have this conversation.

And just as a reminder to everyone, this is not any amount of fearmongering to say that antihistamines are poisonous and you should stop taking them immediately. Talk with your doctor. The idea here is to say, “Hey, if you're taking these long term, maybe you want to talk about with your doctor, are there other options to explore and whether they offer that?” And if they don't, you were saying your clinic, which if you want to share with everyone about your clinic and where you're located, you have a number of offices. And I know that you do accept new patients.

Dr. Thompson: Yeah, we sure do. We've been doing a lot of growth over the last 10 years. We started out in Texas, and we're all over Texas now. We're in Florida in three cities. We're in New Mexico and Albuquerque. We're in Colorado and Denver and Colorado Springs. And we're in Phoenix and Tucson now.

So we're really trying to get the word out because one of the most surprising facts about allergy is that only 2% of the population of allergy patients seek allergy care. Imagine, if 3% of cancer patients or 2% of sleep apnea patients sought and received proper care for their medical ailment? It would just be unfathomable, but yet in the allergy world, again, we're not talking about a life threatening problem in most cases, but it really does get sidelined and poo-pooed by a lot of doctors.

So there's 98% of the allergic population out there that we want to reach. We want to tell them, “Hey, you've got options. There are some real easy treatments like the allergy drops. You don't have to get shots anymore. We have that new ExACT that you do over two months and you're done.” But it's kind of an education campaign really. And that's what we're up against because there's there just isn't much education out there about this.

Jennifer: Well, I'm glad that we were able to connect and make this happen. I'm so excited that you were here. And if anyone is interested in seeing you or any of your colleagues in the clinics in other cities, you can go check out their website at aspireallergy.com or you can check out on Instagram. They have great Instagram posts, @aspireallergy.

Dr. Thompson: There's a lot of A's.

Jennifer: They'll be able to find you. Yes, thank you so much, Dr. Thompson, for being here. I really, really appreciate your time and sharing your wisdom.

Dr. Thompson: Oh, I'm so happy to do it. It was great visiting with you, Jen. Thank you.

“There are some studies that link long-term antihistamine use with things like dementia. There was one I read recently that showed an increase in glial tumors, which are typically brain tumors... There are links to depression. There are links to weight gain with these and all, but one of the antihistamines over-the-counter can cross the blood-brain barrier."